2019-04-30 14:42:43 -04:00
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2005-04-16 15:20:36 -07:00
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2020-12-10 08:55:44 +01:00
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2005-04-16 15:20:36 -07:00
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2020-03-24 08:25:13 +01:00
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2005-04-16 15:20:36 -07:00
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2007-02-20 13:57:48 -08:00
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2005-04-16 15:20:36 -07:00
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2015-05-22 17:13:32 -04:00
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2005-04-16 15:20:36 -07:00
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2008-10-04 23:53:21 +04:00
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2005-04-16 15:20:36 -07:00
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2021-09-20 14:33:25 +02:00
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2006-02-06 14:12:43 -08:00
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2008-08-25 19:47:22 +09:00
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implement in-kernel gendisk events handling
Currently, media presence polling for removeable block devices is done
from userland. There are several issues with this.
* Polling is done by periodically opening the device. For SCSI
devices, the command sequence generated by such action involves a
few different commands including TEST_UNIT_READY. This behavior,
while perfectly legal, is different from Windows which only issues
single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some
ATAPI devices lock up after being periodically queried such command
sequences.
* There is no reliable and unintrusive way for a userland program to
tell whether the target device is safe for media presence polling.
For example, polling for media presence during an on-going burning
session can make it fail. The polling program can avoid this by
opening the device with O_EXCL but then it risks making a valid
exclusive user of the device fail w/ -EBUSY.
* Userland polling is unnecessarily heavy and in-kernel implementation
is lighter and better coordinated (workqueue, timer slack).
This patch implements framework for in-kernel disk event handling,
which includes media presence polling.
* bdops->check_events() is added, which supercedes ->media_changed().
It should check whether there's any pending event and return if so.
Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and
DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be
called parallelly.
* gendisk->events and ->async_events are added. These should be
initialized by block driver before passing the device to add_disk().
The former contains the mask of all supported events and the latter
the mask of all events which the device can report without polling.
/sys/block/*/events[_async] export these to userland.
* Kernel parameter block.events_dfl_poll_msecs controls the system
polling interval (default is 0 which means disable) and
/sys/block/*/events_poll_msecs control polling intervals for
individual devices (default is -1 meaning use system setting). Note
that if a device can report all supported events asynchronously and
its polling interval isn't explicitly set, the device won't be
polled regardless of the system polling interval.
* If a device is opened exclusively with write access, event checking
is automatically disabled until all write exclusive accesses are
released.
* There are event 'clearing' events. For example, both of currently
defined events are cleared after the device has been successfully
opened. This information is passed to ->check_events() callback
using @clearing argument as a hint.
* Event checking is always performed from system_nrt_wq and timer
slack is set to 25% for polling.
* Nothing changes for drivers which implement ->media_changed() but
not ->check_events(). Going forward, all drivers will be converted
to ->check_events() and ->media_change() will be dropped.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 20:57:37 +01:00
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2013-02-22 16:34:13 -08:00
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2016-01-09 08:36:51 -08:00
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2021-11-23 19:53:12 +01:00
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2023-06-10 10:20:03 +08:00
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2005-04-16 15:20:36 -07:00
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2023-06-10 10:20:03 +08:00
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2008-03-04 11:23:45 +01:00
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2021-11-23 19:53:08 +01:00
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2021-09-29 09:12:40 +02:00
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2022-03-08 06:51:55 +01:00
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2008-03-04 11:23:45 +01:00
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2020-03-25 16:48:35 +01:00
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2005-04-16 15:20:36 -07:00
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block: add disk sequence number
Associating uevents with block devices in userspace is difficult and racy:
the uevent netlink socket is lossy, and on slow and overloaded systems
has a very high latency.
Block devices do not have exclusive owners in userspace, any process can
set one up (e.g. loop devices). Moreover, device names can be reused
(e.g. loop0 can be reused again and again). A userspace process setting
up a block device and watching for its events cannot thus reliably tell
whether an event relates to the device it just set up or another earlier
instance with the same name.
Being able to set a UUID on a loop device would solve the race conditions.
But it does not allow to derive orderings from uevents: if you see a
uevent with a UUID that does not match the device you are waiting for,
you cannot tell whether it's because the right uevent has not arrived yet,
or it was already sent and you missed it. So you cannot tell whether you
should wait for it or not.
Associating a unique, monotonically increasing sequential number to the
lifetime of each block device, which can be retrieved with an ioctl
immediately upon setting it up, allows to solve the race conditions with
uevents, and also allows userspace processes to know whether they should
wait for the uevent they need or if it was dropped and thus they should
move on.
Additionally, increment the disk sequence number when the media change,
i.e. on DISK_EVENT_MEDIA_CHANGE event.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-2-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-13 01:05:25 +02:00
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2008-08-25 19:47:22 +09:00
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2013-02-27 17:03:56 -08:00
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2020-11-26 09:23:26 +01:00
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2008-08-25 19:47:22 +09:00
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2020-11-26 18:43:37 +01:00
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2025-01-15 17:26:48 +08:00
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2023-04-24 22:13:18 +09:00
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2020-11-26 18:43:37 +01:00
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2020-03-13 05:30:05 +00:00
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2020-11-16 15:56:56 +01:00
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2020-03-13 05:30:05 +00:00
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2020-11-16 15:56:56 +01:00
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2020-03-13 05:30:05 +00:00
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2020-11-26 18:43:37 +01:00
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2020-03-13 05:30:05 +00:00
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2020-11-26 18:43:37 +01:00
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2021-08-09 08:40:28 +02:00
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2020-11-26 18:43:37 +01:00
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2020-03-13 05:30:05 +00:00
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2025-11-17 13:34:07 +08:00
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2021-02-23 16:50:15 +08:00
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2020-11-12 17:50:04 +01:00
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2020-11-26 18:43:37 +01:00
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2020-03-13 05:30:05 +00:00
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2020-11-16 15:56:56 +01:00
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2020-03-13 05:30:05 +00:00
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2020-11-27 16:43:51 +01:00
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2020-03-25 16:07:06 +03:00
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2020-11-27 16:43:51 +01:00
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2020-03-25 16:07:06 +03:00
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2025-05-06 20:48:59 +08:00
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2025-05-06 20:48:58 +08:00
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2018-04-26 00:21:59 -07:00
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2025-06-26 19:57:43 +08:00
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2018-12-06 11:41:20 -05:00
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2025-05-06 20:48:58 +08:00
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2025-06-26 19:57:43 +08:00
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2018-12-06 11:41:20 -05:00
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2025-05-06 20:48:58 +08:00
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2025-06-26 19:57:43 +08:00
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2018-04-26 00:21:59 -07:00
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2025-05-06 20:48:59 +08:00
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2025-05-06 20:48:55 +08:00
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2025-05-06 20:48:58 +08:00
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2025-05-06 20:48:55 +08:00
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2025-05-06 20:48:59 +08:00
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2025-05-06 20:48:55 +08:00
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2025-05-06 20:48:59 +08:00
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2025-05-06 20:48:55 +08:00
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2005-04-16 15:20:36 -07:00
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2017-06-16 17:48:21 -06:00
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2005-04-16 15:20:36 -07:00
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2022-01-04 08:16:47 +01:00
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2020-10-29 15:58:28 +01:00
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2022-01-04 08:16:47 +01:00
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2006-03-31 02:30:32 -08:00
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2020-10-29 15:58:26 +01:00
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block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
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2005-04-16 15:20:36 -07:00
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2010-12-17 09:00:18 +01:00
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2005-04-16 15:20:36 -07:00
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2006-03-31 02:30:32 -08:00
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2005-04-16 15:20:36 -07:00
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2006-03-31 02:30:32 -08:00
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2008-09-03 09:01:09 +02:00
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2006-01-14 13:20:38 -08:00
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2006-03-31 02:30:32 -08:00
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2006-01-14 13:20:38 -08:00
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block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
|
|
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|
2017-06-16 17:48:21 -06:00
|
|
|
|
|
|
|
|
|
2008-09-03 09:01:09 +02:00
|
|
|
|
block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
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2006-01-14 13:20:38 -08:00
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2006-03-31 02:30:32 -08:00
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2005-04-16 15:20:36 -07:00
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2009-02-20 08:12:51 +01:00
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2020-11-14 18:08:21 +01:00
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2009-02-20 08:12:51 +01:00
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2018-02-05 18:25:27 -08:00
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2009-02-20 08:12:51 +01:00
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2021-11-03 16:04:34 -07:00
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2009-02-20 08:12:51 +01:00
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2017-03-30 17:11:36 -03:00
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2018-02-05 18:25:27 -08:00
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2017-03-30 17:11:36 -03:00
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2009-02-20 08:12:51 +01:00
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2018-02-05 18:25:27 -08:00
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2020-11-14 18:08:21 +01:00
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2009-02-20 08:12:51 +01:00
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2020-10-29 15:58:28 +01:00
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2005-04-16 15:20:36 -07:00
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2020-10-29 15:58:26 +01:00
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2005-04-16 15:20:36 -07:00
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2019-02-17 10:21:56 -05:00
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2005-04-16 15:20:36 -07:00
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2017-06-16 17:48:21 -06:00
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2019-02-17 10:21:56 -05:00
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2017-06-16 17:48:21 -06:00
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2026-02-21 16:37:42 -08:00
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2005-04-16 15:20:36 -07:00
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2022-01-04 08:16:47 +01:00
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2020-10-29 15:58:28 +01:00
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2022-01-04 08:16:47 +01:00
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2023-05-30 15:56:08 +00:00
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2005-04-16 15:20:36 -07:00
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block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
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2005-04-16 15:20:36 -07:00
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block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
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2005-04-16 15:20:36 -07:00
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2018-02-05 18:25:27 -08:00
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2005-04-16 15:20:36 -07:00
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2020-10-29 15:58:26 +01:00
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2005-04-16 15:20:36 -07:00
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2020-10-29 15:58:28 +01:00
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2005-04-16 15:20:36 -07:00
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2007-07-17 04:03:47 -07:00
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2005-04-16 15:20:36 -07:00
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2020-10-29 15:58:26 +01:00
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block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
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2005-04-16 15:20:36 -07:00
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2007-07-17 04:03:45 -07:00
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2005-04-16 15:20:36 -07:00
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block: genhd: don't call blkdev_show() with major_names_lock held
If CONFIG_BLK_DEV_LOOP && CONFIG_MTD (at least; there might be other
combinations), lockdep complains circular locking dependency at
__loop_clr_fd(), for major_names_lock serves as a locking dependency
aggregating hub across multiple block modules.
======================================================
WARNING: possible circular locking dependency detected
5.14.0+ #757 Tainted: G E
------------------------------------------------------
systemd-udevd/7568 is trying to acquire lock:
ffff88800f334d48 ((wq_completion)loop0){+.+.}-{0:0}, at: flush_workqueue+0x70/0x560
but task is already holding lock:
ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #6 (&lo->lo_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_killable_nested+0x17/0x20
lo_open+0x23/0x50 [loop]
blkdev_get_by_dev+0x199/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #5 (&disk->open_mutex){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
bd_register_pending_holders+0x20/0x100
device_add_disk+0x1ae/0x390
loop_add+0x29c/0x2d0 [loop]
blk_request_module+0x5a/0xb0
blkdev_get_no_open+0x27/0xa0
blkdev_get_by_dev+0x5f/0x540
blkdev_open+0x58/0x90
do_dentry_open+0x144/0x3a0
path_openat+0xa57/0xda0
do_filp_open+0x9f/0x140
do_sys_openat2+0x71/0x150
__x64_sys_openat+0x78/0xa0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #4 (major_names_lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
blkdev_show+0x19/0x80
devinfo_show+0x52/0x60
seq_read_iter+0x2d5/0x3e0
proc_reg_read_iter+0x41/0x80
vfs_read+0x2ac/0x330
ksys_read+0x6b/0xd0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #3 (&p->lock){+.+.}-{3:3}:
lock_acquire+0xbe/0x1f0
__mutex_lock_common+0xb6/0xe10
mutex_lock_nested+0x17/0x20
seq_read_iter+0x37/0x3e0
generic_file_splice_read+0xf3/0x170
splice_direct_to_actor+0x14e/0x350
do_splice_direct+0x84/0xd0
do_sendfile+0x263/0x430
__se_sys_sendfile64+0x96/0xc0
do_syscall_64+0x3d/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
-> #2 (sb_writers#3){.+.+}-{0:0}:
lock_acquire+0xbe/0x1f0
lo_write_bvec+0x96/0x280 [loop]
loop_process_work+0xa68/0xc10 [loop]
process_one_work+0x293/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #1 ((work_completion)(&lo->rootcg_work)){+.+.}-{0:0}:
lock_acquire+0xbe/0x1f0
process_one_work+0x280/0x480
worker_thread+0x23d/0x4b0
kthread+0x163/0x180
ret_from_fork+0x1f/0x30
-> #0 ((wq_completion)loop0){+.+.}-{0:0}:
validate_chain+0x1f0d/0x33e0
__lock_acquire+0x92d/0x1030
lock_acquire+0xbe/0x1f0
flush_workqueue+0x8c/0x560
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
__loop_clr_fd+0xb4/0x400 [loop]
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
other info that might help us debug this:
Chain exists of:
(wq_completion)loop0 --> &disk->open_mutex --> &lo->lo_mutex
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&lo->lo_mutex);
lock(&disk->open_mutex);
lock(&lo->lo_mutex);
lock((wq_completion)loop0);
*** DEADLOCK ***
2 locks held by systemd-udevd/7568:
#0: ffff888012554128 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0x4c/0x1d0
#1: ffff888014a7d4a0 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0x4d/0x400 [loop]
stack backtrace:
CPU: 0 PID: 7568 Comm: systemd-udevd Tainted: G E 5.14.0+ #757
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 02/27/2020
Call Trace:
dump_stack_lvl+0x79/0xbf
print_circular_bug+0x5d6/0x5e0
? stack_trace_save+0x42/0x60
? save_trace+0x3d/0x2d0
check_noncircular+0x10b/0x120
validate_chain+0x1f0d/0x33e0
? __lock_acquire+0x953/0x1030
? __lock_acquire+0x953/0x1030
__lock_acquire+0x92d/0x1030
? flush_workqueue+0x70/0x560
lock_acquire+0xbe/0x1f0
? flush_workqueue+0x70/0x560
flush_workqueue+0x8c/0x560
? flush_workqueue+0x70/0x560
? sched_clock_cpu+0xe/0x1a0
? drain_workqueue+0x41/0x140
drain_workqueue+0x80/0x140
destroy_workqueue+0x47/0x4f0
? blk_mq_freeze_queue_wait+0xac/0xd0
__loop_clr_fd+0xb4/0x400 [loop]
? __mutex_unlock_slowpath+0x35/0x230
blkdev_put+0x14a/0x1d0
blkdev_close+0x1c/0x20
__fput+0xfd/0x220
task_work_run+0x69/0xc0
exit_to_user_mode_prepare+0x1ce/0x1f0
syscall_exit_to_user_mode+0x26/0x60
do_syscall_64+0x4c/0xb0
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f0fd4c661f7
Code: 00 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 41 c3 48 83 ec 18 89 7c 24 0c e8 13 fc ff ff
RSP: 002b:00007ffd1c9e9fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f0fd46be6c8 RCX: 00007f0fd4c661f7
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 0000000000000006 R08: 000055fff1eaf400 R09: 0000000000000000
R10: 00007f0fd46be6c8 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000002f08 R15: 00007ffd1c9ea050
Commit 1c500ad706383f1a ("loop: reduce the loop_ctl_mutex scope") is for
breaking "loop_ctl_mutex => &lo->lo_mutex" dependency chain. But enabling
a different block module results in forming circular locking dependency
due to shared major_names_lock mutex.
The simplest fix is to call probe function without holding
major_names_lock [1], but Christoph Hellwig does not like such idea.
Therefore, instead of holding major_names_lock in blkdev_show(),
introduce a different lock for blkdev_show() in order to break
"sb_writers#$N => &p->lock => major_names_lock" dependency chain.
Link: https://lkml.kernel.org/r/b2af8a5b-3c1b-204e-7f56-bea0b15848d6@i-love.sakura.ne.jp [1]
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/18a02da2-0bf3-550e-b071-2b4ab13c49f0@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-09-07 20:52:13 +09:00
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2020-10-29 15:58:26 +01:00
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2005-04-16 15:20:36 -07:00
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2021-05-21 07:50:51 +02:00
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2008-08-25 19:47:22 +09:00
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2013-02-27 17:03:57 -08:00
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2008-08-25 19:47:22 +09:00
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2022-03-26 15:50:46 +01:00
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2021-08-24 09:52:16 +02:00
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2008-08-25 19:47:22 +09:00
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2021-05-21 07:50:51 +02:00
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2008-08-25 19:47:22 +09:00
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2021-08-24 09:52:16 +02:00
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2019-04-02 20:06:34 +08:00
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2021-01-24 11:02:39 +01:00
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2021-04-06 08:23:02 +02:00
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2021-01-24 11:02:39 +01:00
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2021-04-06 08:23:02 +02:00
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2021-07-01 10:16:37 +02:00
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2021-04-06 08:23:02 +02:00
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2021-01-24 11:02:39 +01:00
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2021-07-01 10:16:37 +02:00
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2021-04-06 08:23:02 +02:00
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2021-01-24 11:02:39 +01:00
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2023-06-08 13:02:55 +02:00
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2020-09-21 09:19:46 +02:00
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2024-01-23 14:26:20 +01:00
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2023-02-17 10:22:00 +08:00
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2020-09-21 09:19:46 +02:00
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2024-05-02 15:00:32 +02:00
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2022-05-27 07:58:06 +02:00
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2021-11-22 14:06:16 +01:00
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2020-09-21 09:19:46 +02:00
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2023-02-17 10:22:00 +08:00
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2023-06-08 13:02:55 +02:00
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2023-06-01 11:44:52 +02:00
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2023-02-17 10:22:00 +08:00
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2023-03-22 11:59:26 +08:00
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2024-01-23 14:26:20 +01:00
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2023-02-17 10:22:00 +08:00
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2024-01-23 14:26:20 +01:00
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2023-02-17 10:22:00 +08:00
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2023-03-22 11:59:26 +08:00
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2023-06-08 13:02:55 +02:00
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2023-02-17 10:22:00 +08:00
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2020-09-21 09:19:46 +02:00
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2025-05-05 22:17:45 +08:00
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2025-05-05 22:17:46 +08:00
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2021-08-04 11:41:47 +02:00
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2005-04-16 15:20:36 -07:00
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2021-08-18 16:45:33 +02:00
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2021-05-21 07:50:51 +02:00
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2008-04-30 00:54:32 -07:00
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2025-01-15 17:26:48 +08:00
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2025-01-06 09:35:08 +01:00
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2024-04-12 01:21:45 -04:00
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2025-01-06 09:35:08 +01:00
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2023-04-14 07:32:02 -06:00
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2021-05-21 07:50:51 +02:00
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2008-08-25 19:56:17 +09:00
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2022-10-22 10:16:15 +08:00
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2021-05-21 07:50:51 +02:00
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2021-08-18 16:45:40 +02:00
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2025-05-05 22:17:54 +08:00
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2021-05-21 07:50:52 +02:00
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2023-12-19 15:59:42 +08:00
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2025-05-05 22:17:54 +08:00
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2021-05-21 07:50:51 +02:00
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2021-08-18 16:45:40 +02:00
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2025-05-05 22:17:54 +08:00
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2021-05-21 07:50:51 +02:00
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2021-08-18 16:45:40 +02:00
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2025-05-05 22:17:54 +08:00
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2021-05-21 07:50:51 +02:00
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2021-08-24 09:52:15 +02:00
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2021-05-21 07:50:51 +02:00
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2008-08-25 19:56:17 +09:00
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2021-08-18 16:45:33 +02:00
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2024-10-03 00:11:43 +02:00
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2021-08-18 16:45:34 +02:00
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2021-08-18 16:45:40 +02:00
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2021-12-21 17:18:51 +01:00
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driver core: remove CONFIG_SYSFS_DEPRECATED and CONFIG_SYSFS_DEPRECATED_V2
CONFIG_SYSFS_DEPRECATED was added in commit 88a22c985e35
("CONFIG_SYSFS_DEPRECATED") in 2006 to allow systems with older versions
of some tools (i.e. Fedora 3's version of udev) to boot properly. Four
years later, in 2010, the option was attempted to be removed as most of
userspace should have been fixed up properly by then, but some kernel
developers clung to those old systems and refused to update, so we added
CONFIG_SYSFS_DEPRECATED_V2 in commit e52eec13cd6b ("SYSFS: Allow boot
time switching between deprecated and modern sysfs layout") to allow
them to continue to boot properly, and we allowed a boot time parameter
to be used to switch back to the old format if needed.
Over time, the logic that was covered under these config options was
slowly removed from individual driver subsystems successfully, removed,
and the only thing that is now left in the kernel are some changes in
the block layer's representation in sysfs where real directories are
used instead of symlinks like normal.
Because the original changes were done to userspace tools in 2006, and
all distros that use those tools are long end-of-life, and older
non-udev-based systems do not care about the block layer's sysfs
representation, it is time to finally remove this old logic and the
config entries from the kernel.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-block@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20230223073326.2073220-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-02-23 08:33:26 +01:00
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2021-08-18 16:45:33 +02:00
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2021-11-03 09:40:23 -07:00
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2023-03-18 17:36:25 +00:00
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2021-11-03 09:40:23 -07:00
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2021-08-18 16:45:33 +02:00
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2021-11-03 09:40:23 -07:00
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2021-08-18 16:45:40 +02:00
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2021-11-03 09:40:23 -07:00
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2021-08-18 16:45:33 +02:00
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2021-08-18 16:45:40 +02:00
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2021-08-18 16:45:37 +02:00
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2021-11-22 14:06:23 +01:00
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2021-08-18 16:45:34 +02:00
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2021-08-18 16:45:40 +02:00
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2021-08-18 16:45:34 +02:00
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2021-08-18 16:45:40 +02:00
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2022-10-10 15:18:57 +02:00
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2021-08-18 16:45:33 +02:00
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2021-08-18 16:45:40 +02:00
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2022-10-29 15:13:55 +08:00
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2021-08-18 16:45:40 +02:00
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2022-11-15 22:10:45 +08:00
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2021-08-18 16:45:40 +02:00
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driver core: remove CONFIG_SYSFS_DEPRECATED and CONFIG_SYSFS_DEPRECATED_V2
CONFIG_SYSFS_DEPRECATED was added in commit 88a22c985e35
("CONFIG_SYSFS_DEPRECATED") in 2006 to allow systems with older versions
of some tools (i.e. Fedora 3's version of udev) to boot properly. Four
years later, in 2010, the option was attempted to be removed as most of
userspace should have been fixed up properly by then, but some kernel
developers clung to those old systems and refused to update, so we added
CONFIG_SYSFS_DEPRECATED_V2 in commit e52eec13cd6b ("SYSFS: Allow boot
time switching between deprecated and modern sysfs layout") to allow
them to continue to boot properly, and we allowed a boot time parameter
to be used to switch back to the old format if needed.
Over time, the logic that was covered under these config options was
slowly removed from individual driver subsystems successfully, removed,
and the only thing that is now left in the kernel are some changes in
the block layer's representation in sysfs where real directories are
used instead of symlinks like normal.
Because the original changes were done to userspace tools in 2006, and
all distros that use those tools are long end-of-life, and older
non-udev-based systems do not care about the block layer's sysfs
representation, it is time to finally remove this old logic and the
config entries from the kernel.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-block@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20230223073326.2073220-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-02-23 08:33:26 +01:00
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2023-12-11 15:53:56 +08:00
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2021-08-18 16:45:40 +02:00
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2025-05-05 22:17:54 +08:00
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2021-11-09 16:29:49 -08:00
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2005-04-16 15:20:36 -07:00
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2025-05-05 22:17:46 +08:00
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2024-10-03 00:11:43 +02:00
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2016-06-15 18:17:27 -07:00
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2005-04-16 15:20:36 -07:00
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2023-08-11 12:08:25 +02:00
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2023-06-01 11:44:53 +02:00
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2023-10-17 20:48:22 +02:00
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2023-06-01 11:44:53 +02:00
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2023-08-11 12:08:25 +02:00
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2023-06-01 11:44:53 +02:00
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2024-10-25 08:37:20 +08:00
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2022-02-17 08:52:31 +01:00
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2023-06-01 11:44:47 +02:00
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2023-06-01 11:44:48 +02:00
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2024-10-25 08:37:20 +08:00
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2023-06-01 11:44:48 +02:00
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2023-06-01 11:44:47 +02:00
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2022-11-01 16:00:37 +01:00
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2023-06-01 11:44:47 +02:00
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2024-10-25 08:37:20 +08:00
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2023-08-11 12:08:25 +02:00
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2023-06-01 11:44:53 +02:00
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2023-08-11 12:08:25 +02:00
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2022-02-17 08:52:31 +01:00
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2025-05-05 22:17:46 +08:00
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2005-04-16 15:20:36 -07:00
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2021-09-29 09:12:40 +02:00
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2023-06-01 11:44:50 +02:00
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2024-11-27 21:51:30 +08:00
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2021-09-29 09:12:40 +02:00
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2020-06-19 20:47:25 +00:00
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2021-08-24 16:43:10 +02:00
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2020-10-29 15:58:24 +01:00
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implement in-kernel gendisk events handling
Currently, media presence polling for removeable block devices is done
from userland. There are several issues with this.
* Polling is done by periodically opening the device. For SCSI
devices, the command sequence generated by such action involves a
few different commands including TEST_UNIT_READY. This behavior,
while perfectly legal, is different from Windows which only issues
single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some
ATAPI devices lock up after being periodically queried such command
sequences.
* There is no reliable and unintrusive way for a userland program to
tell whether the target device is safe for media presence polling.
For example, polling for media presence during an on-going burning
session can make it fail. The polling program can avoid this by
opening the device with O_EXCL but then it risks making a valid
exclusive user of the device fail w/ -EBUSY.
* Userland polling is unnecessarily heavy and in-kernel implementation
is lighter and better coordinated (workqueue, timer slack).
This patch implements framework for in-kernel disk event handling,
which includes media presence polling.
* bdops->check_events() is added, which supercedes ->media_changed().
It should check whether there's any pending event and return if so.
Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and
DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be
called parallelly.
* gendisk->events and ->async_events are added. These should be
initialized by block driver before passing the device to add_disk().
The former contains the mask of all supported events and the latter
the mask of all events which the device can report without polling.
/sys/block/*/events[_async] export these to userland.
* Kernel parameter block.events_dfl_poll_msecs controls the system
polling interval (default is 0 which means disable) and
/sys/block/*/events_poll_msecs control polling intervals for
individual devices (default is -1 meaning use system setting). Note
that if a device can report all supported events asynchronously and
its polling interval isn't explicitly set, the device won't be
polled regardless of the system polling interval.
* If a device is opened exclusively with write access, event checking
is automatically disabled until all write exclusive accesses are
released.
* There are event 'clearing' events. For example, both of currently
defined events are cleared after the device has been successfully
opened. This information is passed to ->check_events() callback
using @clearing argument as a hint.
* Event checking is always performed from system_nrt_wq and timer
slack is set to 25% for polling.
* Nothing changes for drivers which implement ->media_changed() but
not ->check_events(). Going forward, all drivers will be converted
to ->check_events() and ->media_change() will be dropped.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 20:57:37 +01:00
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2023-06-01 11:44:50 +02:00
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2023-08-11 12:08:25 +02:00
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2023-06-01 11:44:50 +02:00
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2021-05-25 08:12:56 +02:00
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2023-08-11 12:08:25 +02:00
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2024-04-28 19:01:39 -04:00
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2021-05-25 08:12:56 +02:00
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2021-04-06 08:22:56 +02:00
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2023-08-11 12:08:25 +02:00
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2021-09-29 09:12:40 +02:00
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2023-06-01 11:44:50 +02:00
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2024-10-25 08:37:20 +08:00
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2024-11-27 21:51:30 +08:00
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2023-06-01 11:44:50 +02:00
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2020-10-29 15:58:24 +01:00
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2017-11-02 21:29:53 +03:00
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2020-10-29 15:58:24 +01:00
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2017-03-08 17:48:33 +01:00
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2021-08-09 16:17:43 +02:00
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2017-03-08 17:48:33 +01:00
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2010-12-08 20:57:36 +01:00
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2020-10-29 15:58:24 +01:00
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2010-12-08 20:57:36 +01:00
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2020-11-26 18:47:17 +01:00
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2010-12-08 20:57:36 +01:00
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2022-11-15 22:10:45 +08:00
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2010-12-08 20:57:36 +01:00
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2020-11-24 09:36:54 +01:00
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2020-11-26 18:47:17 +01:00
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|
driver core: remove CONFIG_SYSFS_DEPRECATED and CONFIG_SYSFS_DEPRECATED_V2
CONFIG_SYSFS_DEPRECATED was added in commit 88a22c985e35
("CONFIG_SYSFS_DEPRECATED") in 2006 to allow systems with older versions
of some tools (i.e. Fedora 3's version of udev) to boot properly. Four
years later, in 2010, the option was attempted to be removed as most of
userspace should have been fixed up properly by then, but some kernel
developers clung to those old systems and refused to update, so we added
CONFIG_SYSFS_DEPRECATED_V2 in commit e52eec13cd6b ("SYSFS: Allow boot
time switching between deprecated and modern sysfs layout") to allow
them to continue to boot properly, and we allowed a boot time parameter
to be used to switch back to the old format if needed.
Over time, the logic that was covered under these config options was
slowly removed from individual driver subsystems successfully, removed,
and the only thing that is now left in the kernel are some changes in
the block layer's representation in sysfs where real directories are
used instead of symlinks like normal.
Because the original changes were done to userspace tools in 2006, and
all distros that use those tools are long end-of-life, and older
non-udev-based systems do not care about the block layer's sysfs
representation, it is time to finally remove this old logic and the
config entries from the kernel.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-block@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20230223073326.2073220-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-02-23 08:33:26 +01:00
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2013-02-22 16:34:13 -08:00
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2010-12-08 20:57:36 +01:00
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2021-10-26 18:12:04 +08:00
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2022-09-19 16:40:49 +02:00
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2022-09-21 20:04:58 +02:00
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2022-03-18 21:01:44 +08:00
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2021-10-26 18:12:04 +08:00
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2022-10-30 17:47:30 +08:00
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2022-06-14 09:48:24 +02:00
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2021-10-26 18:12:04 +08:00
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2022-06-19 08:05:51 +02:00
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2021-10-26 18:12:04 +08:00
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2024-11-04 19:00:05 +08:00
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2022-06-19 08:05:51 +02:00
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2024-11-04 19:00:05 +08:00
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2024-10-25 08:37:20 +08:00
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2024-11-27 21:51:30 +08:00
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2005-04-16 15:20:36 -07:00
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2025-05-05 22:17:46 +08:00
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2025-05-05 22:17:58 +08:00
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2025-05-05 22:17:46 +08:00
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2025-11-25 16:11:13 +00:00
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2025-05-05 22:17:46 +08:00
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2025-11-25 16:11:13 +00:00
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2025-05-05 22:17:46 +08:00
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2025-05-05 22:17:58 +08:00
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2025-05-05 22:17:46 +08:00
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2010-12-08 20:57:36 +01:00
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2005-04-16 15:20:36 -07:00
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2021-09-22 20:37:08 +08:00
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2024-04-11 15:53:37 +01:00
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2021-09-22 20:37:08 +08:00
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2016-01-09 08:36:51 -08:00
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2024-11-07 18:42:58 +08:00
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2016-01-09 08:36:51 -08:00
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2022-01-04 08:16:47 +01:00
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2024-12-09 19:04:35 +08:00
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2020-10-29 15:58:27 +01:00
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2020-10-29 15:58:28 +01:00
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2024-12-09 19:04:35 +08:00
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2020-10-29 15:58:28 +01:00
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2024-12-09 19:04:35 +08:00
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2020-10-29 15:58:28 +01:00
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2024-12-09 19:04:35 +08:00
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2020-10-29 15:58:27 +01:00
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2022-01-04 08:16:47 +01:00
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2020-10-29 15:58:27 +01:00
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2005-04-16 15:20:36 -07:00
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2008-09-03 08:57:12 +02:00
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2008-05-22 17:21:08 -04:00
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2008-09-03 08:57:12 +02:00
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2008-05-22 17:21:08 -04:00
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2026-02-21 16:37:42 -08:00
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2008-09-03 08:57:12 +02:00
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2008-05-22 17:21:08 -04:00
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2008-09-03 08:57:12 +02:00
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2005-04-16 15:20:36 -07:00
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2007-05-21 22:08:01 +02:00
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2008-05-22 17:21:08 -04:00
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2008-09-03 08:57:12 +02:00
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2008-09-03 08:53:37 +02:00
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2008-05-22 17:21:08 -04:00
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2008-09-03 08:53:37 +02:00
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2005-04-16 15:20:36 -07:00
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2008-09-03 08:57:12 +02:00
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2008-05-22 17:21:08 -04:00
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2008-09-03 08:57:12 +02:00
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2008-05-22 17:21:08 -04:00
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2008-09-03 08:57:12 +02:00
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2016-07-29 10:40:31 +02:00
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2008-08-16 14:30:30 +02:00
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2005-04-16 15:20:36 -07:00
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2008-09-03 08:57:12 +02:00
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2005-04-16 15:20:36 -07:00
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block: Don't use static to define "void *p" in show_partition_start()
I met a odd prblem:read /proc/partitions may return zero.
I wrote a file test.c:
int main()
{
char buff[4096];
int ret;
int fd;
printf("pid=%d\n",getpid());
while (1) {
fd = open("/proc/partitions", O_RDONLY);
if (fd < 0) {
printf("open error %s\n", strerror(errno));
return 0;
}
ret = read(fd, buff, 4096);
if (ret <= 0)
printf("ret=%d, %s, %ld\n", ret,
strerror(errno), lseek(fd,0,SEEK_CUR));
close(fd);
}
exit(0);
}
You can reproduce by:
1:while true;do cat /proc/partitions > /dev/null ;done
2:./test
I reviewed the code and found:
>> static void *show_partition_start(struct seq_file *seqf, loff_t *pos)
>> {
>> static void *p;
>>
>> p = disk_seqf_start(seqf, pos);
>> if (!IS_ERR_OR_NULL(p) && !*pos)
>> seq_puts(seqf, "major minor #blocks name\n\n");
>> return p;
>> }
test cat /proc/partitions
p = disk_seqf_start()(Not NULL)
p = disk_seqf_start()(NULL because pos)
if (!IS_ERR_OR_NULL(p) && !*pos)
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-08-03 10:42:00 +02:00
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2008-09-03 08:57:12 +02:00
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2010-12-17 08:58:36 +01:00
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2008-09-03 08:57:12 +02:00
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2005-04-16 15:20:36 -07:00
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2008-09-03 09:01:09 +02:00
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2005-04-16 15:20:36 -07:00
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2020-11-24 09:52:59 +01:00
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2021-04-06 08:23:00 +02:00
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2005-04-16 15:20:36 -07:00
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2021-11-22 14:06:21 +01:00
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2005-04-16 15:20:36 -07:00
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2021-04-06 08:23:00 +02:00
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2021-07-27 08:25:15 +02:00
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2020-11-24 09:52:59 +01:00
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2021-07-27 08:25:15 +02:00
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2021-04-06 08:23:00 +02:00
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2005-04-16 15:20:36 -07:00
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2008-10-04 23:53:21 +04:00
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2008-09-03 08:57:12 +02:00
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2007-05-21 22:08:01 +02:00
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2005-04-16 15:20:36 -07:00
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2008-04-21 10:51:07 -07:00
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2008-03-11 17:13:15 -07:00
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2005-04-16 15:20:36 -07:00
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2007-05-21 22:08:01 +02:00
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block: fix boot failure with CONFIG_DEBUG_BLOCK_EXT_DEVT=y and nash
We run into system boot failure with kernel 2.6.28-rc. We found it on a
couple of machines, including T61 notebook, nehalem machine, and another
HPC NX6325 notebook. All the machines use FedoraCore 8 or FedoraCore 9.
With kernel prior to 2.6.28-rc, system boot doesn't fail.
I debug it and locate the root cause. Pls. see
http://bugzilla.kernel.org/show_bug.cgi?id=11899
https://bugzilla.redhat.com/show_bug.cgi?id=471517
As a matter of fact, there are 2 bugs.
1)root=/dev/sda1, system boot randomly fails. Mostly, boot for 5 times
and fails once. nash has a bug. Some of its functions misuse return
value 0. Sometimes, 0 means timeout and no uevent available. Sometimes,
0 means nash gets an uevent, but the uevent isn't block-related (for
exmaple, usb). If by coincidence, kernel tells nash that uevents are
available, but kernel also set timeout, nash might stops collecting
other uevents in queue if current uevent isn't block-related. I work
out a patch for nash to fix it.
http://bugzilla.kernel.org/attachment.cgi?id=18858
2) root=LABEL=/, system always can't boot. initrd init reports
switchroot fails. Here is an executation branch of nash when booting:
(1) nash read /sys/block/sda/dev; Assume major is 8 (on my desktop)
(2) nash query /proc/devices with the major number; It found line
"8 sd";
(3) nash use 'sd' to search its own probe table to find device (DISK)
type for the device and add it to its own list;
(4) Later on, it probes all devices in its list to get filesystem
labels; scsi register "8 sd" always.
When major is 259, nash fails to find the device(DISK) type. I enables
CONFIG_DEBUG_BLOCK_EXT_DEVT=y when compiling kernel, so 259 is picked up
for device /dev/sda1, which causes nash to fail to find device (DISK)
type.
To fixing issue 2), I create a patch for nash and another patch for
kernel.
http://bugzilla.kernel.org/attachment.cgi?id=18859
http://bugzilla.kernel.org/attachment.cgi?id=18837
Below is the patch for kernel 2.6.28-rc4. It registers blkext, a new
block device in proc/devices.
With 2 patches on nash and 1 patch on kernel, I boot my machines for
dozens of times without failure.
Signed-off-by Zhang Yanmin <yanmin.zhang@linux.intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-11-14 08:26:30 +01:00
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2007-05-21 22:08:01 +02:00
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driver core: remove CONFIG_SYSFS_DEPRECATED and CONFIG_SYSFS_DEPRECATED_V2
CONFIG_SYSFS_DEPRECATED was added in commit 88a22c985e35
("CONFIG_SYSFS_DEPRECATED") in 2006 to allow systems with older versions
of some tools (i.e. Fedora 3's version of udev) to boot properly. Four
years later, in 2010, the option was attempted to be removed as most of
userspace should have been fixed up properly by then, but some kernel
developers clung to those old systems and refused to update, so we added
CONFIG_SYSFS_DEPRECATED_V2 in commit e52eec13cd6b ("SYSFS: Allow boot
time switching between deprecated and modern sysfs layout") to allow
them to continue to boot properly, and we allowed a boot time parameter
to be used to switch back to the old format if needed.
Over time, the logic that was covered under these config options was
slowly removed from individual driver subsystems successfully, removed,
and the only thing that is now left in the kernel are some changes in
the block layer's representation in sysfs where real directories are
used instead of symlinks like normal.
Because the original changes were done to userspace tools in 2006, and
all distros that use those tools are long end-of-life, and older
non-udev-based systems do not care about the block layer's sysfs
representation, it is time to finally remove this old logic and the
config entries from the kernel.
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: linux-block@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20230223073326.2073220-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-02-23 08:33:26 +01:00
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|
2007-11-06 10:36:58 -08:00
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2005-04-16 15:20:36 -07:00
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2007-05-21 22:08:01 +02:00
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2005-04-16 15:20:36 -07:00
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2007-05-21 22:08:01 +02:00
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2005-04-16 15:20:36 -07:00
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2024-11-07 18:42:58 +08:00
|
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2005-04-16 15:20:36 -07:00
|
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2008-08-25 19:47:23 +09:00
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2024-11-07 18:42:58 +08:00
|
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2021-11-22 14:06:22 +01:00
|
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2008-08-25 19:47:23 +09:00
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2007-05-21 22:08:01 +02:00
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2005-10-01 14:49:43 +02:00
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2007-05-21 22:08:01 +02:00
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2005-10-01 14:49:43 +02:00
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2024-11-07 18:42:58 +08:00
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2005-04-16 15:20:36 -07:00
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2007-05-21 22:08:01 +02:00
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2005-04-16 15:20:36 -07:00
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2017-11-02 21:29:53 +03:00
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2024-11-07 18:42:58 +08:00
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2017-11-02 21:29:53 +03:00
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2008-06-13 09:41:00 +02:00
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2024-11-07 18:42:58 +08:00
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2008-06-13 09:41:00 +02:00
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2020-03-24 08:25:13 +01:00
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2024-11-07 18:42:58 +08:00
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2020-03-24 08:25:13 +01:00
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2020-11-27 16:43:51 +01:00
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2020-03-25 16:07:06 +03:00
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2020-03-24 08:25:13 +01:00
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2025-05-06 20:48:59 +08:00
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2022-02-17 14:42:47 +08:00
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2024-11-07 18:42:58 +08:00
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2020-03-24 08:25:13 +01:00
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2020-03-25 16:07:06 +03:00
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2020-03-24 08:25:13 +01:00
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2020-03-25 16:07:06 +03:00
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2020-03-25 16:07:08 +03:00
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2020-03-25 16:07:06 +03:00
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2020-03-24 08:25:13 +01:00
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2025-05-06 20:48:58 +08:00
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2020-03-24 08:25:13 +01:00
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2020-11-27 16:43:51 +01:00
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2021-10-14 15:03:30 +01:00
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2025-05-06 20:48:58 +08:00
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2020-03-24 08:25:13 +01:00
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2025-05-06 20:48:59 +08:00
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2020-05-13 12:49:33 +02:00
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2025-05-06 20:48:58 +08:00
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2020-03-24 08:25:13 +01:00
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2007-05-21 22:08:01 +02:00
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2007-05-23 13:57:38 -07:00
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2023-02-03 16:02:09 +01:00
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2024-11-07 18:42:58 +08:00
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2007-05-23 13:57:38 -07:00
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2007-05-21 22:08:01 +02:00
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2009-05-22 17:17:53 -04:00
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2024-11-07 18:42:58 +08:00
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2009-05-22 17:17:53 -04:00
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2009-11-10 11:50:21 +01:00
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2024-11-07 18:42:58 +08:00
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2009-11-10 11:50:21 +01:00
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2021-07-13 01:05:28 +02:00
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2024-11-07 18:42:58 +08:00
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2021-07-13 01:05:28 +02:00
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2024-05-02 15:00:33 +02:00
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2024-11-07 18:42:58 +08:00
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2024-05-02 15:00:33 +02:00
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2018-05-24 13:38:59 -06:00
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2021-07-13 01:05:28 +02:00
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2024-05-02 15:00:33 +02:00
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2020-03-24 08:25:13 +01:00
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2006-12-08 02:39:46 -08:00
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2020-03-24 08:25:13 +01:00
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2024-11-07 18:42:58 +08:00
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2024-04-28 00:15:07 -04:00
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2020-03-24 08:25:13 +01:00
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2024-04-28 00:15:07 -04:00
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2020-03-24 08:25:13 +01:00
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2007-05-21 22:08:01 +02:00
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2018-05-24 13:38:59 -06:00
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2020-03-24 08:25:13 +01:00
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2008-09-14 05:56:33 -07:00
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2018-05-24 13:38:59 -06:00
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2008-09-14 05:56:33 -07:00
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2007-05-21 22:08:01 +02:00
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2008-08-25 19:47:23 +09:00
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2007-05-21 22:08:01 +02:00
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2017-11-02 21:29:53 +03:00
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2008-06-13 09:41:00 +02:00
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2007-05-21 22:08:01 +02:00
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2009-05-22 17:17:53 -04:00
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2009-11-10 11:50:21 +01:00
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2007-05-21 22:08:01 +02:00
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block: Seperate read and write statistics of in_flight requests v2
Commit a9327cac440be4d8333bba975cbbf76045096275 added seperate read
and write statistics of in_flight requests. And exported the number
of read and write requests in progress seperately through sysfs.
But Corrado Zoccolo <czoccolo@gmail.com> reported getting strange
output from "iostat -kx 2". Global values for service time and
utilization were garbage. For interval values, utilization was always
100%, and service time is higher than normal.
So this was reverted by commit 0f78ab9899e9d6acb09d5465def618704255963b
The problem was in part_round_stats_single(), I missed the following:
if (now == part->stamp)
return;
- if (part->in_flight) {
+ if (part_in_flight(part)) {
__part_stat_add(cpu, part, time_in_queue,
part_in_flight(part) * (now - part->stamp));
__part_stat_add(cpu, part, io_ticks, (now - part->stamp));
With this chunk included, the reported regression gets fixed.
Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
--
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2009-10-06 20:16:55 +02:00
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2016-01-09 08:36:51 -08:00
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2021-06-24 09:38:43 +02:00
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2021-07-13 01:05:28 +02:00
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2024-05-02 15:00:33 +02:00
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2007-05-21 22:08:01 +02:00
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2008-09-14 05:56:33 -07:00
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2007-05-21 22:08:01 +02:00
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2005-04-16 15:20:36 -07:00
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2017-04-27 14:46:26 -07:00
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2007-05-21 22:08:01 +02:00
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2017-04-27 14:46:26 -07:00
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2007-05-21 22:08:01 +02:00
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2009-06-24 10:06:31 -07:00
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2007-05-21 22:08:01 +02:00
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2022-06-28 19:18:45 +02:00
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2023-03-18 17:36:25 +00:00
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2022-06-28 19:18:45 +02:00
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2007-05-21 22:08:01 +02:00
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2020-06-19 20:47:23 +00:00
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2025-11-25 16:11:13 +00:00
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2020-06-19 20:47:23 +00:00
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2020-06-19 20:47:25 +00:00
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2020-06-19 20:47:23 +00:00
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2007-05-21 22:08:01 +02:00
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2005-04-16 15:20:36 -07:00
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2007-05-21 22:08:01 +02:00
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2020-06-19 20:47:25 +00:00
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2021-10-14 15:02:31 +02:00
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2020-06-19 20:47:25 +00:00
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2023-06-10 10:20:03 +08:00
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2022-07-20 15:05:41 +02:00
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block: stop the timeout timer when releasing a never added disk
disk_release() undoes blk_mq_init_allocated_queue() for a disk whose
probe failed before add_disk(), but it only calls blk_mq_exit_queue().
Nothing there stops q->timeout, and that timer rolls forward: it stays
pending until it next expires, not until the last request completes.
So if the driver issued any I/O before adding the disk, the
request_queue is freed while still linked into a timer wheel bucket.
Commit 6f8191fdf41d ("block: simplify disk shutdown") dropped the
blk_cleanup_queue() call that used to stop it. __del_gendisk() and
blk_mq_destroy_queue() still do; only the probe failure path lost it.
nvme gets there because nvme_update_ns_info() submits Report Zones or
FDP io-mgmt-recv on ns->queue before the disk is added, so a later
failure - a concurrent reset setting NVME_CTRL_FROZEN, or
device_add_disk() failing - lands in put_disk() with the timer armed:
BUG: KASAN: slab-use-after-free in detach_if_pending+0x30c/0x340
Write of size 8 at addr ffff888004d71310 by task kworker/u8:2/37
__timer_delete_sync+0x156/0x240 kernel/time/timer.c:1621
blk_sync_queue+0x22/0x40 block/blk-core.c:222
nvme_sync_queues+0x100/0x150 drivers/nvme/host/core.c:5362
nvme_reset_work+0x138/0x930 drivers/nvme/host/pci.c:3264
Allocated by task 34:
__blk_mq_alloc_disk+0x33/0x100 block/blk-mq.c:4462
nvme_alloc_ns+0x290/0x3870 drivers/nvme/host/core.c:4146
Freed by task 0:
blk_free_queue_rcu+0x3a/0x50 block/blk-core.c:254
rcu_core+0xc10/0x1730 kernel/rcu/tree.c:2857
The queue being synced there is ctrl->admin_q, only a victim sharing a
timer wheel bucket with the freed queue's dangling entry; other runs
tripped in enqueue_timer(), __run_timers() or blk_mq_timeout_work().
Failing nvme_alloc_ns() with a debug patch makes it deterministic: one
leaked timer trips KASAN within seconds, while 1987 patched releases
produced no splat.
Stop the timer and the queue work items before blk_mq_exit_queue(), like
blk_mq_destroy_queue() does.
Found by FuzzNvme.
Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Acked-by: Weidong Zhu <weizhu@fiu.edu>
Signed-off-by: Chao Shi <coshi036@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260727201257.211635-1-coshi036@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2026-07-27 16:12:57 -04:00
|
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2022-07-20 15:05:41 +02:00
|
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|
block: stop the timeout timer when releasing a never added disk
disk_release() undoes blk_mq_init_allocated_queue() for a disk whose
probe failed before add_disk(), but it only calls blk_mq_exit_queue().
Nothing there stops q->timeout, and that timer rolls forward: it stays
pending until it next expires, not until the last request completes.
So if the driver issued any I/O before adding the disk, the
request_queue is freed while still linked into a timer wheel bucket.
Commit 6f8191fdf41d ("block: simplify disk shutdown") dropped the
blk_cleanup_queue() call that used to stop it. __del_gendisk() and
blk_mq_destroy_queue() still do; only the probe failure path lost it.
nvme gets there because nvme_update_ns_info() submits Report Zones or
FDP io-mgmt-recv on ns->queue before the disk is added, so a later
failure - a concurrent reset setting NVME_CTRL_FROZEN, or
device_add_disk() failing - lands in put_disk() with the timer armed:
BUG: KASAN: slab-use-after-free in detach_if_pending+0x30c/0x340
Write of size 8 at addr ffff888004d71310 by task kworker/u8:2/37
__timer_delete_sync+0x156/0x240 kernel/time/timer.c:1621
blk_sync_queue+0x22/0x40 block/blk-core.c:222
nvme_sync_queues+0x100/0x150 drivers/nvme/host/core.c:5362
nvme_reset_work+0x138/0x930 drivers/nvme/host/pci.c:3264
Allocated by task 34:
__blk_mq_alloc_disk+0x33/0x100 block/blk-mq.c:4462
nvme_alloc_ns+0x290/0x3870 drivers/nvme/host/core.c:4146
Freed by task 0:
blk_free_queue_rcu+0x3a/0x50 block/blk-core.c:254
rcu_core+0xc10/0x1730 kernel/rcu/tree.c:2857
The queue being synced there is ctrl->admin_q, only a victim sharing a
timer wheel bucket with the freed queue's dangling entry; other runs
tripped in enqueue_timer(), __run_timers() or blk_mq_timeout_work().
Failing nvme_alloc_ns() with a debug patch makes it deterministic: one
leaked timer trips KASAN within seconds, while 1987 patched releases
produced no splat.
Stop the timer and the queue work items before blk_mq_exit_queue(), like
blk_mq_destroy_queue() does.
Found by FuzzNvme.
Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Acked-by: Weidong Zhu <weizhu@fiu.edu>
Signed-off-by: Chao Shi <coshi036@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260727201257.211635-1-coshi036@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2026-07-27 16:12:57 -04:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2022-07-20 15:05:41 +02:00
|
|
|
|
block: stop the timeout timer when releasing a never added disk
disk_release() undoes blk_mq_init_allocated_queue() for a disk whose
probe failed before add_disk(), but it only calls blk_mq_exit_queue().
Nothing there stops q->timeout, and that timer rolls forward: it stays
pending until it next expires, not until the last request completes.
So if the driver issued any I/O before adding the disk, the
request_queue is freed while still linked into a timer wheel bucket.
Commit 6f8191fdf41d ("block: simplify disk shutdown") dropped the
blk_cleanup_queue() call that used to stop it. __del_gendisk() and
blk_mq_destroy_queue() still do; only the probe failure path lost it.
nvme gets there because nvme_update_ns_info() submits Report Zones or
FDP io-mgmt-recv on ns->queue before the disk is added, so a later
failure - a concurrent reset setting NVME_CTRL_FROZEN, or
device_add_disk() failing - lands in put_disk() with the timer armed:
BUG: KASAN: slab-use-after-free in detach_if_pending+0x30c/0x340
Write of size 8 at addr ffff888004d71310 by task kworker/u8:2/37
__timer_delete_sync+0x156/0x240 kernel/time/timer.c:1621
blk_sync_queue+0x22/0x40 block/blk-core.c:222
nvme_sync_queues+0x100/0x150 drivers/nvme/host/core.c:5362
nvme_reset_work+0x138/0x930 drivers/nvme/host/pci.c:3264
Allocated by task 34:
__blk_mq_alloc_disk+0x33/0x100 block/blk-mq.c:4462
nvme_alloc_ns+0x290/0x3870 drivers/nvme/host/core.c:4146
Freed by task 0:
blk_free_queue_rcu+0x3a/0x50 block/blk-core.c:254
rcu_core+0xc10/0x1730 kernel/rcu/tree.c:2857
The queue being synced there is ctrl->admin_q, only a victim sharing a
timer wheel bucket with the freed queue's dangling entry; other runs
tripped in enqueue_timer(), __run_timers() or blk_mq_timeout_work().
Failing nvme_alloc_ns() with a debug patch makes it deterministic: one
leaked timer trips KASAN within seconds, while 1987 patched releases
produced no splat.
Stop the timer and the queue work items before blk_mq_exit_queue(), like
blk_mq_destroy_queue() does.
Found by FuzzNvme.
Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Acked-by: Weidong Zhu <weizhu@fiu.edu>
Signed-off-by: Chao Shi <coshi036@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260727201257.211635-1-coshi036@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2026-07-27 16:12:57 -04:00
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2022-07-20 15:05:41 +02:00
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2023-02-14 19:33:06 +01:00
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2022-07-27 12:22:57 -04:00
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blk-mq: cancel blk-mq dispatch work in both blk_cleanup_queue and disk_release()
For avoiding to slow down queue destroy, we don't call
blk_mq_quiesce_queue() in blk_cleanup_queue(), instead of delaying to
cancel dispatch work in blk_release_queue().
However, this way has caused kernel oops[1], reported by Changhui. The log
shows that scsi_device can be freed before running blk_release_queue(),
which is expected too since scsi_device is released after the scsi disk
is closed and the scsi_device is removed.
Fixes the issue by canceling blk-mq dispatch work in both blk_cleanup_queue()
and disk_release():
1) when disk_release() is run, the disk has been closed, and any sync
dispatch activities have been done, so canceling dispatch work is enough to
quiesce filesystem I/O dispatch activity.
2) in blk_cleanup_queue(), we only focus on passthrough request, and
passthrough request is always explicitly allocated & freed by
its caller, so once queue is frozen, all sync dispatch activity
for passthrough request has been done, then it is enough to just cancel
dispatch work for avoiding any dispatch activity.
[1] kernel panic log
[12622.769416] BUG: kernel NULL pointer dereference, address: 0000000000000300
[12622.777186] #PF: supervisor read access in kernel mode
[12622.782918] #PF: error_code(0x0000) - not-present page
[12622.788649] PGD 0 P4D 0
[12622.791474] Oops: 0000 [#1] PREEMPT SMP PTI
[12622.796138] CPU: 10 PID: 744 Comm: kworker/10:1H Kdump: loaded Not tainted 5.15.0+ #1
[12622.804877] Hardware name: Dell Inc. PowerEdge R730/0H21J3, BIOS 1.5.4 10/002/2015
[12622.813321] Workqueue: kblockd blk_mq_run_work_fn
[12622.818572] RIP: 0010:sbitmap_get+0x75/0x190
[12622.823336] Code: 85 80 00 00 00 41 8b 57 08 85 d2 0f 84 b1 00 00 00 45 31 e4 48 63 cd 48 8d 1c 49 48 c1 e3 06 49 03 5f 10 4c 8d 6b 40 83 f0 01 <48> 8b 33 44 89 f2 4c 89 ef 0f b6 c8 e8 fa f3 ff ff 83 f8 ff 75 58
[12622.844290] RSP: 0018:ffffb00a446dbd40 EFLAGS: 00010202
[12622.850120] RAX: 0000000000000001 RBX: 0000000000000300 RCX: 0000000000000004
[12622.858082] RDX: 0000000000000006 RSI: 0000000000000082 RDI: ffffa0b7a2dfe030
[12622.866042] RBP: 0000000000000004 R08: 0000000000000001 R09: ffffa0b742721334
[12622.874003] R10: 0000000000000008 R11: 0000000000000008 R12: 0000000000000000
[12622.881964] R13: 0000000000000340 R14: 0000000000000000 R15: ffffa0b7a2dfe030
[12622.889926] FS: 0000000000000000(0000) GS:ffffa0baafb40000(0000) knlGS:0000000000000000
[12622.898956] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[12622.905367] CR2: 0000000000000300 CR3: 0000000641210001 CR4: 00000000001706e0
[12622.913328] Call Trace:
[12622.916055] <TASK>
[12622.918394] scsi_mq_get_budget+0x1a/0x110
[12622.922969] __blk_mq_do_dispatch_sched+0x1d4/0x320
[12622.928404] ? pick_next_task_fair+0x39/0x390
[12622.933268] __blk_mq_sched_dispatch_requests+0xf4/0x140
[12622.939194] blk_mq_sched_dispatch_requests+0x30/0x60
[12622.944829] __blk_mq_run_hw_queue+0x30/0xa0
[12622.949593] process_one_work+0x1e8/0x3c0
[12622.954059] worker_thread+0x50/0x3b0
[12622.958144] ? rescuer_thread+0x370/0x370
[12622.962616] kthread+0x158/0x180
[12622.966218] ? set_kthread_struct+0x40/0x40
[12622.970884] ret_from_fork+0x22/0x30
[12622.974875] </TASK>
[12622.977309] Modules linked in: scsi_debug rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs sunrpc dm_multipath intel_rapl_msr intel_rapl_common dell_wmi_descriptor sb_edac rfkill video x86_pkg_temp_thermal intel_powerclamp dcdbas coretemp kvm_intel kvm mgag200 irqbypass i2c_algo_bit rapl drm_kms_helper ipmi_ssif intel_cstate intel_uncore syscopyarea sysfillrect sysimgblt fb_sys_fops pcspkr cec mei_me lpc_ich mei ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter drm fuse xfs libcrc32c sr_mod cdrom sd_mod t10_pi sg ixgbe ahci libahci crct10dif_pclmul crc32_pclmul crc32c_intel libata megaraid_sas ghash_clmulni_intel tg3 wdat_wdt mdio dca wmi dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_debug]
Reported-by: ChanghuiZhong <czhong@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20211116014343.610501-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-16 09:43:43 +08:00
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implement in-kernel gendisk events handling
Currently, media presence polling for removeable block devices is done
from userland. There are several issues with this.
* Polling is done by periodically opening the device. For SCSI
devices, the command sequence generated by such action involves a
few different commands including TEST_UNIT_READY. This behavior,
while perfectly legal, is different from Windows which only issues
single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some
ATAPI devices lock up after being periodically queried such command
sequences.
* There is no reliable and unintrusive way for a userland program to
tell whether the target device is safe for media presence polling.
For example, polling for media presence during an on-going burning
session can make it fail. The polling program can avoid this by
opening the device with O_EXCL but then it risks making a valid
exclusive user of the device fail w/ -EBUSY.
* Userland polling is unnecessarily heavy and in-kernel implementation
is lighter and better coordinated (workqueue, timer slack).
This patch implements framework for in-kernel disk event handling,
which includes media presence polling.
* bdops->check_events() is added, which supercedes ->media_changed().
It should check whether there's any pending event and return if so.
Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and
DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be
called parallelly.
* gendisk->events and ->async_events are added. These should be
initialized by block driver before passing the device to add_disk().
The former contains the mask of all supported events and the latter
the mask of all events which the device can report without polling.
/sys/block/*/events[_async] export these to userland.
* Kernel parameter block.events_dfl_poll_msecs controls the system
polling interval (default is 0 which means disable) and
/sys/block/*/events_poll_msecs control polling intervals for
individual devices (default is -1 meaning use system setting). Note
that if a device can report all supported events asynchronously and
its polling interval isn't explicitly set, the device won't be
polled regardless of the system polling interval.
* If a device is opened exclusively with write access, event checking
is automatically disabled until all write exclusive accesses are
released.
* There are event 'clearing' events. For example, both of currently
defined events are cleared after the device has been successfully
opened. This information is passed to ->check_events() callback
using @clearing argument as a hint.
* Event checking is always performed from system_nrt_wq and timer
slack is set to 25% for polling.
* Nothing changes for drivers which implement ->media_changed() but
not ->check_events(). Going forward, all drivers will be converted
to ->check_events() and ->media_change() will be dropped.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-08 20:57:37 +01:00
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2005-04-16 15:20:36 -07:00
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2026-07-01 17:21:55 +09:00
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2021-01-24 11:02:41 +01:00
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2022-03-08 06:51:55 +01:00
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2025-08-08 13:36:09 +08:00
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2021-08-16 15:46:24 +02:00
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2021-08-16 15:19:09 +02:00
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2022-02-15 10:45:10 +01:00
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2024-04-28 19:01:39 -04:00
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2005-04-16 15:20:36 -07:00
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2021-07-13 01:05:26 +02:00
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2022-11-23 13:25:19 +01:00
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2021-07-13 01:05:26 +02:00
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2022-11-23 13:25:19 +01:00
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2021-07-13 01:05:26 +02:00
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2024-03-05 16:32:16 -03:00
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2007-05-21 22:08:01 +02:00
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2021-07-13 01:05:26 +02:00
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2005-04-16 15:20:36 -07:00
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2023-01-11 12:30:08 +01:00
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2023-01-04 14:44:02 -07:00
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2020-06-01 13:12:05 -07:00
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2007-05-21 22:08:01 +02:00
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2023-01-04 14:44:02 -07:00
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2005-04-16 15:20:36 -07:00
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2008-05-23 09:44:11 -07:00
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2008-09-03 09:01:09 +02:00
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2005-04-16 15:20:36 -07:00
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2020-11-24 09:52:59 +01:00
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2018-12-06 11:41:21 -05:00
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2020-03-25 16:07:06 +03:00
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2021-04-06 08:23:01 +02:00
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2005-04-16 15:20:36 -07:00
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2008-08-25 19:56:05 +09:00
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2008-09-03 09:01:09 +02:00
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2005-04-16 15:20:36 -07:00
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2011-06-13 10:45:43 +02:00
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2021-04-06 08:23:01 +02:00
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2020-03-25 16:07:06 +03:00
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2025-05-06 20:48:59 +08:00
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2022-02-17 14:42:47 +08:00
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2024-11-08 13:45:00 +08:00
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2005-04-16 15:20:36 -07:00
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2021-04-06 08:23:01 +02:00
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2011-06-13 10:45:43 +02:00
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2005-04-16 15:20:36 -07:00
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2008-10-06 12:55:38 +04:00
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2008-09-03 08:57:12 +02:00
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2005-04-16 15:20:36 -07:00
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2008-10-04 23:53:21 +04:00
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2018-04-13 19:44:18 +02:00
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2008-10-04 23:53:21 +04:00
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2008-05-23 09:44:11 -07:00
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2005-04-16 15:20:36 -07:00
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2021-05-25 08:13:00 +02:00
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2021-05-25 08:13:01 +02:00
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2021-05-25 08:13:00 +02:00
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2021-05-25 08:13:01 +02:00
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2021-05-25 08:13:00 +02:00
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2021-05-25 08:13:01 +02:00
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2021-05-25 08:13:00 +02:00
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2021-08-16 15:19:08 +02:00
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2005-06-23 00:08:19 -07:00
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2013-08-29 15:21:42 -07:00
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2020-08-31 20:02:37 +02:00
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2022-08-11 20:23:37 -03:00
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2011-01-07 08:43:37 +01:00
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2022-07-27 12:22:57 -04:00
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2021-08-09 16:17:43 +02:00
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2022-07-27 12:22:57 -04:00
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2021-08-09 16:17:43 +02:00
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2021-10-14 15:03:26 +01:00
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2020-11-26 18:47:17 +01:00
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2021-08-09 16:17:43 +02:00
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2008-09-03 09:06:42 +02:00
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2020-08-31 20:02:37 +02:00
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2021-05-25 08:12:56 +02:00
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2021-01-24 11:02:41 +01:00
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2020-08-31 20:02:37 +02:00
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2023-02-14 19:33:06 +01:00
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block: Introduce zone write plugging
Zone write plugging implements a per-zone "plug" for write operations
to control the submission and execution order of write operations to
sequential write required zones of a zoned block device. Per-zone
plugging guarantees that at any time there is at most only one write
request per zone being executed. This mechanism is intended to replace
zone write locking which implements a similar per-zone write throttling
at the scheduler level, but is implemented only by mq-deadline.
Unlike zone write locking which operates on requests, zone write
plugging operates on BIOs. A zone write plug is simply a BIO list that
is atomically manipulated using a spinlock and a kblockd submission
work. A write BIO to a zone is "plugged" to delay its execution if a
write BIO for the same zone was already issued, that is, if a write
request for the same zone is being executed. The next plugged BIO is
unplugged and issued once the write request completes.
This mechanism allows to:
- Untangle zone write ordering from block IO schedulers. This allows
removing the restriction on using mq-deadline for writing to zoned
block devices. Any block IO scheduler, including "none" can be used.
- Zone write plugging operates on BIOs instead of requests. Plugged
BIOs waiting for execution thus do not hold scheduling tags and thus
are not preventing other BIOs from executing (reads or writes to
other zones). Depending on the workload, this can significantly
improve the device use (higher queue depth operation) and
performance.
- Both blk-mq (request based) zoned devices and BIO-based zoned devices
(e.g. device mapper) can use zone write plugging. It is mandatory
for the former but optional for the latter. BIO-based drivers can
use zone write plugging to implement write ordering guarantees, or
the drivers can implement their own if needed.
- The code is less invasive in the block layer and is mostly limited to
blk-zoned.c with some small changes in blk-mq.c, blk-merge.c and
bio.c.
Zone write plugging is implemented using struct blk_zone_wplug. This
structure includes a spinlock, a BIO list and a work structure to
handle the submission of plugged BIOs. Zone write plugs structures are
managed using a per-disk hash table.
Plugging of zone write BIOs is done using the function
blk_zone_write_plug_bio() which returns false if a BIO execution does
not need to be delayed and true otherwise. This function is called
from blk_mq_submit_bio() after a BIO is split to avoid large BIOs
spanning multiple zones which would cause mishandling of zone write
plugs. This ichange enables by default zone write plugging for any mq
request-based block device. BIO-based device drivers can also use zone
write plugging by expliclty calling blk_zone_write_plug_bio() in their
->submit_bio method. For such devices, the driver must ensure that a
BIO passed to blk_zone_write_plug_bio() is already split and not
straddling zone boundaries.
Only write and write zeroes BIOs are plugged. Zone write plugging does
not introduce any significant overhead for other operations. A BIO that
is being handled through zone write plugging is flagged using the new
BIO flag BIO_ZONE_WRITE_PLUGGING. A request handling a BIO flagged with
this new flag is flagged with the new RQF_ZONE_WRITE_PLUGGING flag.
The completion of BIOs and requests flagged trigger respectively calls
to the functions blk_zone_write_bio_endio() and
blk_zone_write_complete_request(). The latter function is used to
trigger submission of the next plugged BIO using the zone plug work.
blk_zone_write_bio_endio() does the same for BIO-based devices.
This ensures that at any time, at most one request (blk-mq devices) or
one BIO (BIO-based devices) is being executed for any zone. The
handling of zone write plugs using a per-zone plug spinlock maximizes
parallelism and device usage by allowing multiple zones to be writen
simultaneously without lock contention.
Zone write plugging ignores flush BIOs without data. Hovever, any flush
BIO that has data is always plugged so that the write part of the flush
sequence is serialized with other regular writes.
Given that any BIO handled through zone write plugging will be the only
BIO in flight for the target zone when it is executed, the unplugging
and submission of a BIO will have no chance of successfully merging with
plugged requests or requests in the scheduler. To overcome this
potential performance degradation, blk_mq_submit_bio() calls the
function blk_zone_write_plug_attempt_merge() to try to merge other
plugged BIOs with the one just unplugged and submitted. Successful
merging is signaled using blk_zone_write_plug_bio_merged(), called from
bio_attempt_back_merge(). Furthermore, to avoid recalculating the number
of segments of plugged BIOs to attempt merging, the number of segments
of a plugged BIO is saved using the new struct bio field
__bi_nr_segments. To avoid growing the size of struct bio, this field is
added as a union with the bio_cookie field. This is safe to do as
polling is always disabled for plugged BIOs.
When BIOs are plugged in a zone write plug, the device request queue
usage counter is always incremented. This reference is kept and reused
for blk-mq devices when the plugged BIO is unplugged and submitted
again using submit_bio_noacct_nocheck(). For this case, the unplugged
BIO is already flagged with BIO_ZONE_WRITE_PLUGGING and
blk_mq_submit_bio() proceeds directly to allocating a new request for
the BIO, re-using the usage reference count taken when the BIO was
plugged. This extra reference count is dropped in
blk_zone_write_plug_attempt_merge() for any plugged BIO that is
successfully merged. Given that BIO-based devices will not take this
path, the extra reference is dropped after a plugged BIO is unplugged
and submitted.
Zone write plugs are dynamically allocated and managed using a hash
table (an array of struct hlist_head) with RCU protection.
A zone write plug is allocated when a write BIO is received for the
zone and not freed until the zone is fully written, reset or finished.
To detect when a zone write plug can be freed, the write state of each
zone is tracked using a write pointer offset which corresponds to the
offset of a zone write pointer relative to the zone start. Write
operations always increment this write pointer offset. Zone reset
operations set it to 0 and zone finish operations set it to the zone
size.
If a write error happens, the wp_offset value of a zone write plug may
become incorrect and out of sync with the device managed write pointer.
This is handled using the zone write plug flag BLK_ZONE_WPLUG_ERROR.
The function blk_zone_wplug_handle_error() is called from the new disk
zone write plug work when this flag is set. This function executes a
report zone to update the zone write pointer offset to the current
value as indicated by the device. The disk zone write plug work is
scheduled whenever a BIO flagged with BIO_ZONE_WRITE_PLUGGING completes
with an error or when bio_zone_wplug_prepare_bio() detects an unaligned
write. Once scheduled, the disk zone write plugs work keeps running
until all zone errors are handled.
To match the new data structures used for zoned disks, the function
disk_free_zone_bitmaps() is renamed to the more generic
disk_free_zone_resources(). The function disk_init_zone_resources() is
also introduced to initialize zone write plugs resources when a gendisk
is allocated.
In order to guarantee that the user can simultaneously write up to a
number of zones equal to a device max active zone limit or max open zone
limit, zone write plugs are allocated using a mempool sized to the
maximum of these 2 device limits. For a device that does not have
active and open zone limits, 128 is used as the default mempool size.
If a change to the device active and open zone limits is detected, the
disk mempool is resized when blk_revalidate_disk_zones() is executed.
This commit contains contributions from Christoph Hellwig <hch@lst.de>.
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Tested-by: Hans Holmberg <hans.holmberg@wdc.com>
Tested-by: Dennis Maisenbacher <dennis.maisenbacher@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240408014128.205141-8-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-08 10:41:07 +09:00
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block: add disk sequence number
Associating uevents with block devices in userspace is difficult and racy:
the uevent netlink socket is lossy, and on slow and overloaded systems
has a very high latency.
Block devices do not have exclusive owners in userspace, any process can
set one up (e.g. loop devices). Moreover, device names can be reused
(e.g. loop0 can be reused again and again). A userspace process setting
up a block device and watching for its events cannot thus reliably tell
whether an event relates to the device it just set up or another earlier
instance with the same name.
Being able to set a UUID on a loop device would solve the race conditions.
But it does not allow to derive orderings from uevents: if you see a
uevent with a UUID that does not match the device you are waiting for,
you cannot tell whether it's because the right uevent has not arrived yet,
or it was already sent and you missed it. So you cannot tell whether you
should wait for it or not.
Associating a unique, monotonically increasing sequential number to the
lifetime of each block device, which can be retrieved with an ioctl
immediately upon setting it up, allows to solve the race conditions with
uevents, and also allows userspace processes to know whether they should
wait for the uevent they need or if it was dropped and thus they should
move on.
Additionally, increment the disk sequence number when the media change,
i.e. on DISK_EVENT_MEDIA_CHANGE event.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-2-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-13 01:05:25 +02:00
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2021-08-16 15:46:24 +02:00
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2021-08-16 15:19:05 +02:00
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2021-08-04 11:41:42 +02:00
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2026-06-11 16:06:47 +02:00
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2009-07-28 09:13:13 +02:00
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2021-01-09 11:42:51 +01:00
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2021-01-29 05:55:05 +01:00
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2021-01-09 11:42:51 +01:00
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2005-04-16 15:20:36 -07:00
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block: add disk sequence number
Associating uevents with block devices in userspace is difficult and racy:
the uevent netlink socket is lossy, and on slow and overloaded systems
has a very high latency.
Block devices do not have exclusive owners in userspace, any process can
set one up (e.g. loop devices). Moreover, device names can be reused
(e.g. loop0 can be reused again and again). A userspace process setting
up a block device and watching for its events cannot thus reliably tell
whether an event relates to the device it just set up or another earlier
instance with the same name.
Being able to set a UUID on a loop device would solve the race conditions.
But it does not allow to derive orderings from uevents: if you see a
uevent with a UUID that does not match the device you are waiting for,
you cannot tell whether it's because the right uevent has not arrived yet,
or it was already sent and you missed it. So you cannot tell whether you
should wait for it or not.
Associating a unique, monotonically increasing sequential number to the
lifetime of each block device, which can be retrieved with an ioctl
immediately upon setting it up, allows to solve the race conditions with
uevents, and also allows userspace processes to know whether they should
wait for the uevent they need or if it was dropped and thus they should
move on.
Additionally, increment the disk sequence number when the media change,
i.e. on DISK_EVENT_MEDIA_CHANGE event.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Tested-by: Luca Boccassi <bluca@debian.org>
Link: https://lore.kernel.org/r/20210712230530.29323-2-mcroce@linux.microsoft.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-07-13 01:05:25 +02:00
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