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Jens Axboe d7b2abd87d dm: don't attempt to queue IO under RCU protection 
commit a9ce385344 upstream.

dm looks up the table for IO based on the request type, with an
assumption that if the request is marked REQ_NOWAIT, it's fine to
attempt to submit that IO while under RCU read lock protection. This
is not OK, as REQ_NOWAIT just means that we should not be sleeping
waiting on other IO, it does not mean that we can't potentially
schedule.

A simple test case demonstrates this quite nicely:

int main(int argc, char *argv[])
{
        struct iovec iov;
        int fd;

        fd = open("/dev/dm-0", O_RDONLY | O_DIRECT);
        posix_memalign(&iov.iov_base, 4096, 4096);
        iov.iov_len = 4096;
        preadv2(fd, &iov, 1, 0, RWF_NOWAIT);
        return 0;
}

which will instantly spew:

BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 5580, name: dm-nowait
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
INFO: lockdep is turned off.
CPU: 7 PID: 5580 Comm: dm-nowait Not tainted 6.6.0-rc1-g39956d2dcd81 #132
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x11d/0x1b0
 __might_resched+0x3c3/0x5e0
 ? preempt_count_sub+0x150/0x150
 mempool_alloc+0x1e2/0x390
 ? mempool_resize+0x7d0/0x7d0
 ? lock_sync+0x190/0x190
 ? lock_release+0x4b7/0x670
 ? internal_get_user_pages_fast+0x868/0x2d40
 bio_alloc_bioset+0x417/0x8c0
 ? bvec_alloc+0x200/0x200
 ? internal_get_user_pages_fast+0xb8c/0x2d40
 bio_alloc_clone+0x53/0x100
 dm_submit_bio+0x27f/0x1a20
 ? lock_release+0x4b7/0x670
 ? blk_try_enter_queue+0x1a0/0x4d0
 ? dm_dax_direct_access+0x260/0x260
 ? rcu_is_watching+0x12/0xb0
 ? blk_try_enter_queue+0x1cc/0x4d0
 __submit_bio+0x239/0x310
 ? __bio_queue_enter+0x700/0x700
 ? kvm_clock_get_cycles+0x40/0x60
 ? ktime_get+0x285/0x470
 submit_bio_noacct_nocheck+0x4d9/0xb80
 ? should_fail_request+0x80/0x80
 ? preempt_count_sub+0x150/0x150
 ? lock_release+0x4b7/0x670
 ? __bio_add_page+0x143/0x2d0
 ? iov_iter_revert+0x27/0x360
 submit_bio_noacct+0x53e/0x1b30
 submit_bio_wait+0x10a/0x230
 ? submit_bio_wait_endio+0x40/0x40
 __blkdev_direct_IO_simple+0x4f8/0x780
 ? blkdev_bio_end_io+0x4c0/0x4c0
 ? stack_trace_save+0x90/0xc0
 ? __bio_clone+0x3c0/0x3c0
 ? lock_release+0x4b7/0x670
 ? lock_sync+0x190/0x190
 ? atime_needs_update+0x3bf/0x7e0
 ? timestamp_truncate+0x21b/0x2d0
 ? inode_owner_or_capable+0x240/0x240
 blkdev_direct_IO.part.0+0x84a/0x1810
 ? rcu_is_watching+0x12/0xb0
 ? lock_release+0x4b7/0x670
 ? blkdev_read_iter+0x40d/0x530
 ? reacquire_held_locks+0x4e0/0x4e0
 ? __blkdev_direct_IO_simple+0x780/0x780
 ? rcu_is_watching+0x12/0xb0
 ? __mark_inode_dirty+0x297/0xd50
 ? preempt_count_add+0x72/0x140
 blkdev_read_iter+0x2a4/0x530
 do_iter_readv_writev+0x2f2/0x3c0
 ? generic_copy_file_range+0x1d0/0x1d0
 ? fsnotify_perm.part.0+0x25d/0x630
 ? security_file_permission+0xd8/0x100
 do_iter_read+0x31b/0x880
 ? import_iovec+0x10b/0x140
 vfs_readv+0x12d/0x1a0
 ? vfs_iter_read+0xb0/0xb0
 ? rcu_is_watching+0x12/0xb0
 ? rcu_is_watching+0x12/0xb0
 ? lock_release+0x4b7/0x670
 do_preadv+0x1b3/0x260
 ? do_readv+0x370/0x370
 __x64_sys_preadv2+0xef/0x150
 do_syscall_64+0x39/0xb0
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f5af41ad806
Code: 41 54 41 89 fc 55 44 89 c5 53 48 89 cb 48 83 ec 18 80 3d e4 dd 0d 00 00 74 7a 45 89 c1 49 89 ca 45 31 c0 b8 47 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 be 00 00 00 48 85 c0 79 4a 48 8b 0d da 55
RSP: 002b:00007ffd3145c7f0 EFLAGS: 00000246 ORIG_RAX: 0000000000000147
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5af41ad806
RDX: 0000000000000001 RSI: 00007ffd3145c850 RDI: 0000000000000003
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000008
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007ffd3145c850 R14: 000055f5f0431dd8 R15: 0000000000000001
 </TASK>

where in fact it is dm itself that attempts to allocate a bio clone with
GFP_NOIO under the rcu read lock, regardless of the request type.

Fix this by getting rid of the special casing for REQ_NOWAIT, and just
use the normal SRCU protected table lookup. Get rid of the bio based
table locking helpers at the same time, as they are now unused.

Cc: stable@vger.kernel.org
Fixes: 563a225c9f ("dm: introduce dm_{get,put}_live_table_bio called from dm_submit_bio")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-09-23 11:11:10 +02:00
arch x86/purgatory: Remove LTO flags 2023-09-23 11:11:09 +02:00
block block: factor out a bvec_set_page helper 2023-09-23 11:11:08 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: lrw,xts - Replace strlcpy with strscpy 2023-09-23 11:11:01 +02:00
Documentation perf/smmuv3: Enable HiSilicon Erratum 162001900 quirk for HIP08/09 2023-09-23 11:11:00 +02:00
drivers dm: don't attempt to queue IO under RCU protection 2023-09-23 11:11:10 +02:00
fs ovl: fix incorrect fdput() on aio completion 2023-09-23 11:11:10 +02:00
include x86/ibt: Suppress spurious ENDBR 2023-09-23 11:11:09 +02:00
init sched/psi: Select KERNFS as needed 2023-09-13 09:42:28 +02:00
io_uring io_uring/net: fix iter retargeting for selected buf 2023-09-23 11:11:10 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel panic: Reenable preemption in WARN slowpath 2023-09-23 11:11:09 +02:00
lib kobject: Add sanity check for kset->kobj.ktype in kset_register() 2023-09-23 11:11:07 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm Multi-gen LRU: avoid race in inc_min_seq() 2023-09-19 12:28:04 +02:00
net Revert "SUNRPC: Fail faster on bad verifier" 2023-09-23 11:11:09 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples samples/hw_breakpoint: fix building without module unloading 2023-09-23 11:11:09 +02:00
scripts kconfig: fix possible buffer overflow 2023-09-19 12:27:59 +02:00
security smackfs: Prevent underflow in smk_set_cipso() 2023-09-13 09:42:42 +02:00
sound ALSA: hda: intel-dsp-cfg: add LunarLake support 2023-09-23 11:11:04 +02:00
tools selftests: tracing: Fix to unmount tracefs for recovering environment 2023-09-23 11:11:09 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.54 2023-09-19 12:28:10 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.