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Jan Kara 589f6fac5c rq-qos: fix missed wake-ups in rq_qos_throttle try two 
commit 11c7aa0dde upstream.

Commit 545fbd0775 ("rq-qos: fix missed wake-ups in rq_qos_throttle")
tried to fix a problem that a process could be sleeping in rq_qos_wait()
without anyone to wake it up. However the fix is not complete and the
following can still happen:

CPU1 (waiter1)		CPU2 (waiter2)		CPU3 (waker)
rq_qos_wait()		rq_qos_wait()
  acquire_inflight_cb() -> fails
			  acquire_inflight_cb() -> fails

						completes IOs, inflight
						  decreased
  prepare_to_wait_exclusive()
			  prepare_to_wait_exclusive()
  has_sleeper = !wq_has_single_sleeper() -> true as there are two sleepers
			  has_sleeper = !wq_has_single_sleeper() -> true
  io_schedule()		  io_schedule()

Deadlock as now there's nobody to wakeup the two waiters. The logic
automatically blocking when there are already sleepers is really subtle
and the only way to make it work reliably is that we check whether there
are some waiters in the queue when adding ourselves there. That way, we
are guaranteed that at least the first process to enter the wait queue
will recheck the waiting condition before going to sleep and thus
guarantee forward progress.

Fixes: 545fbd0775 ("rq-qos: fix missed wake-ups in rq_qos_throttle")
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210607112613.25344-1-jack@suse.cz
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2021-07-19 10:04:52 +02:00
..
partitions block/partitions/efi.c: Fix the efi_partition() kernel-doc header 2021-05-14 09:00:06 -06:00
badblocks.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
bfq-cgroup.c block, bfq: merge bursts of newly-created queues 2021-03-25 10:50:07 -06:00
bfq-iosched.c block, bfq: reset waker pointer with shared queues 2021-07-14 17:06:52 +02:00
bfq-iosched.h block, bfq: merge bursts of newly-created queues 2021-03-25 10:50:07 -06:00
bfq-wf2q.c block, bfq: always inject I/O of queues blocked by wakers 2021-03-25 10:50:07 -06:00
bio-integrity.c block: remove BLK_BOUNCE_ISA support 2021-04-06 09:28:17 -06:00
bio.c block: fix trace completion for chained bio 2021-07-14 17:06:53 +02:00
blk-cgroup-rwstat.c blk-cgroup: Fix the recursive blkg rwstat 2021-03-05 11:32:15 -07:00
blk-cgroup-rwstat.h blk-cgroup: separate out blkg_rwstat under CONFIG_BLK_CGROUP_RWSTAT 2019-11-07 12:28:13 -07:00
blk-cgroup.c cgroup: rstat: punt root-level optimization to individual controllers 2021-04-30 11:20:37 -07:00
blk-core.c block: refactor the bounce buffering code 2021-04-06 09:28:17 -06:00
blk-crypto-fallback.c block: rename BIO_MAX_PAGES to BIO_MAX_VECS 2021-03-11 07:47:48 -07:00
blk-crypto-internal.h block: make blk_crypto_rq_bio_prep() able to fail 2020-10-05 10:47:43 -06:00
blk-crypto.c dm: support key eviction from keyslot managers of underlying devices 2021-02-11 09:45:25 -05:00
blk-exec.c block: drop removed argument from kernel-doc of blk_execute_rq() 2021-01-29 07:43:29 -07:00
blk-flush.c block: avoid double io accounting for flush request 2021-07-14 17:06:50 +02:00
blk-integrity.c block: remove the unused blk_integrity_merge_bio export 2020-10-06 07:29:53 -06:00
blk-ioc.c block: remove retry loop in ioc_release_fn() 2020-07-16 10:22:15 -06:00
blk-iocost.c blk-iocost: fix weight updates of inner active iocgs 2021-05-11 20:50:35 -06:00
blk-iolatency.c block: Remove redundant 'return' statement 2020-10-08 07:59:48 -06:00
blk-lib.c block: rename BIO_MAX_PAGES to BIO_MAX_VECS 2021-03-11 07:47:48 -07:00
blk-map.c block: remove an incorrect check from blk_rq_append_bio 2021-04-12 06:45:12 -06:00
blk-merge.c block: fix discard request merge 2021-07-14 17:06:37 +02:00
blk-mq-cpumap.c blk-mq: remove the calling of local_memory_node() 2020-10-20 07:08:17 -06:00
blk-mq-debugfs-zoned.c block: Cleanup license notice 2019-01-17 21:21:40 -07:00
blk-mq-debugfs.c for-5.13/block-2021-04-27 2021-04-28 14:27:12 -07:00
blk-mq-debugfs.h blk-mq: no need to check return value of debugfs_create functions 2019-06-13 03:00:30 -06:00
blk-mq-pci.c block: Fix blk_mq_*_map_queues() kernel-doc headers 2019-05-31 15:12:34 -06:00
blk-mq-rdma.c block: Fix blk_mq_*_map_queues() kernel-doc headers 2019-05-31 15:12:34 -06:00
blk-mq-sched.c kyber: fix out of bounds access when preempted 2021-05-11 08:12:14 -06:00
blk-mq-sched.h block: get rid of the trace rq insert wrapper 2021-02-22 06:37:41 -07:00
blk-mq-sysfs.c blk-mq: move cancel of hctx->run_work to the front of blk_exit_queue 2020-10-09 12:46:28 -06:00
blk-mq-tag.c blk-mq: clear stale request in tags->rq[] before freeing one request pool 2021-07-14 17:06:31 +02:00
blk-mq-tag.h blk-mq: clear stale request in tags->rq[] before freeing one request pool 2021-07-14 17:06:31 +02:00
blk-mq-virtio.c blk-mq: Fix typo in comment 2020-03-17 20:55:21 +01:00
blk-mq.c blk-mq: update hctx->dispatch_busy in case of real scheduler 2021-07-14 17:06:53 +02:00
blk-mq.h blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter 2021-07-14 17:06:31 +02:00
blk-pm.c scsi: block: Fix a race in the runtime power management code 2020-12-09 11:41:41 -05:00
blk-pm.h block: Remove unused blk_pm_*() function definitions 2021-02-22 06:33:48 -07:00
blk-rq-qos.c rq-qos: fix missed wake-ups in rq_qos_throttle try two 2021-07-19 10:04:52 +02:00
blk-rq-qos.h block: fix race between adding/removing rq qos and normal IO 2021-07-14 17:06:34 +02:00
blk-settings.c block-5.13-2021-05-09 2021-05-09 13:25:14 -07:00
blk-stat.c blk-stat: make q->stats->lock irqsafe 2020-09-01 16:48:46 -06:00
blk-stat.h block: deactivate blk_stat timer in wbt_disable_default() 2018-12-12 06:47:51 -07:00
blk-sysfs.c block: add sysfs entry for virt boundary mask 2021-04-06 09:23:23 -06:00
blk-throttle.c block: store a block_device pointer in struct bio 2021-01-24 18:17:20 -07:00
blk-timeout.c block: blk-timeout: delete duplicated word 2020-07-31 16:29:47 -06:00
blk-wbt.c blk-wbt: make sure throttle is enabled properly 2021-07-14 17:06:52 +02:00
blk-wbt.h blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled() 2021-07-14 17:06:52 +02:00
blk-zoned.c blk-zoned: Remove the definition of blk_zone_start() 2021-04-07 14:31:45 -06:00
blk.h block: refactor blk_drop_partitions 2021-04-08 10:24:36 -06:00
bounce.c block: stop calling blk_queue_bounce for passthrough requests 2021-04-06 09:28:18 -06:00
bsg-lib.c block: drop double zeroing 2020-09-23 09:18:13 -06:00
bsg.c block: remove unnecessary argument from blk_execute_rq 2021-01-24 21:52:39 -07:00
cmdline-parser.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
elevator.c blk-mq: set default elevator as deadline in case of hctx shared tagset 2021-04-07 10:15:23 -06:00
genhd.c block: prevent block device lookups at the beginning of del_gendisk 2021-05-20 07:59:35 -06:00
ioctl.c block: return -EBUSY when there are open partitions in blkdev_reread_part 2021-04-21 10:49:37 -06:00
ioprio.c block: Fix sys_ioprio_set(.which=IOPRIO_WHO_PGRP) task iteration 2021-04-08 13:43:53 -06:00
Kconfig blk-wbt: Remove obsolete multiqueue I/O scheduling comment 2020-09-01 16:49:26 -06:00
Kconfig.iosched treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
keyslot-manager.c - Fix DM integrity's HMAC support to provide enhanced security of 2021-02-22 10:22:54 -08:00
kyber-iosched.c kyber: fix out of bounds access when preempted 2021-05-11 08:12:14 -06:00
Makefile blk-mq: merge blk-softirq.c into blk-mq.c 2020-06-24 09:15:56 -06:00
mq-deadline.c kyber: fix out of bounds access when preempted 2021-05-11 08:12:14 -06:00
opal_proto.h block: sed-opal: Change the check condition for regular session validity 2020-03-12 08:00:10 -06:00
scsi_ioctl.c block: Remove an obsolete comment from sg_io() 2021-04-13 11:23:52 -06:00
sed-opal.c block: sed-opal: Change the check condition for regular session validity 2020-03-12 08:00:10 -06:00
t10-pi.c block: Allow t10-pi to be modular 2020-01-06 20:59:04 -07:00