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| author | Mikulas Patocka <mpatocka@redhat.com> | 2019-08-08 17:17:01 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-08-08 18:12:21 +0200 |
| commit | d0a255e795ab976481565f6ac178314b34fbf891 (patch) | |
| tree | 2b8892d852f271573516310f24f6007f9ddded69 /drivers/block | |
| parent | bdev: Fixup error handling in blkdev_get() (diff) | |
| download | linux-d0a255e795ab976481565f6ac178314b34fbf891.tar.xz linux-d0a255e795ab976481565f6ac178314b34fbf891.zip | |
loop: set PF_MEMALLOC_NOIO for the worker thread
A deadlock with this stacktrace was observed.
The loop thread does a GFP_KERNEL allocation, it calls into dm-bufio
shrinker and the shrinker depends on I/O completion in the dm-bufio
subsystem.
In order to fix the deadlock (and other similar ones), we set the flag
PF_MEMALLOC_NOIO at loop thread entry.
PID: 474 TASK: ffff8813e11f4600 CPU: 10 COMMAND: "kswapd0"
#0 [ffff8813dedfb938] __schedule at ffffffff8173f405
#1 [ffff8813dedfb990] schedule at ffffffff8173fa27
#2 [ffff8813dedfb9b0] schedule_timeout at ffffffff81742fec
#3 [ffff8813dedfba60] io_schedule_timeout at ffffffff8173f186
#4 [ffff8813dedfbaa0] bit_wait_io at ffffffff8174034f
#5 [ffff8813dedfbac0] __wait_on_bit at ffffffff8173fec8
#6 [ffff8813dedfbb10] out_of_line_wait_on_bit at ffffffff8173ff81
#7 [ffff8813dedfbb90] __make_buffer_clean at ffffffffa038736f [dm_bufio]
#8 [ffff8813dedfbbb0] __try_evict_buffer at ffffffffa0387bb8 [dm_bufio]
#9 [ffff8813dedfbbd0] dm_bufio_shrink_scan at ffffffffa0387cc3 [dm_bufio]
#10 [ffff8813dedfbc40] shrink_slab at ffffffff811a87ce
#11 [ffff8813dedfbd30] shrink_zone at ffffffff811ad778
#12 [ffff8813dedfbdc0] kswapd at ffffffff811ae92f
#13 [ffff8813dedfbec0] kthread at ffffffff810a8428
#14 [ffff8813dedfbf50] ret_from_fork at ffffffff81745242
PID: 14127 TASK: ffff881455749c00 CPU: 11 COMMAND: "loop1"
#0 [ffff88272f5af228] __schedule at ffffffff8173f405
#1 [ffff88272f5af280] schedule at ffffffff8173fa27
#2 [ffff88272f5af2a0] schedule_preempt_disabled at ffffffff8173fd5e
#3 [ffff88272f5af2b0] __mutex_lock_slowpath at ffffffff81741fb5
#4 [ffff88272f5af330] mutex_lock at ffffffff81742133
#5 [ffff88272f5af350] dm_bufio_shrink_count at ffffffffa03865f9 [dm_bufio]
#6 [ffff88272f5af380] shrink_slab at ffffffff811a86bd
#7 [ffff88272f5af470] shrink_zone at ffffffff811ad778
#8 [ffff88272f5af500] do_try_to_free_pages at ffffffff811adb34
#9 [ffff88272f5af590] try_to_free_pages at ffffffff811adef8
#10 [ffff88272f5af610] __alloc_pages_nodemask at ffffffff811a09c3
#11 [ffff88272f5af710] alloc_pages_current at ffffffff811e8b71
#12 [ffff88272f5af760] new_slab at ffffffff811f4523
#13 [ffff88272f5af7b0] __slab_alloc at ffffffff8173a1b5
#14 [ffff88272f5af880] kmem_cache_alloc at ffffffff811f484b
#15 [ffff88272f5af8d0] do_blockdev_direct_IO at ffffffff812535b3
#16 [ffff88272f5afb00] __blockdev_direct_IO at ffffffff81255dc3
#17 [ffff88272f5afb30] xfs_vm_direct_IO at ffffffffa01fe3fc [xfs]
#18 [ffff88272f5afb90] generic_file_read_iter at ffffffff81198994
#19 [ffff88272f5afc50] __dta_xfs_file_read_iter_2398 at ffffffffa020c970 [xfs]
#20 [ffff88272f5afcc0] lo_rw_aio at ffffffffa0377042 [loop]
#21 [ffff88272f5afd70] loop_queue_work at ffffffffa0377c3b [loop]
#22 [ffff88272f5afe60] kthread_worker_fn at ffffffff810a8a0c
#23 [ffff88272f5afec0] kthread at ffffffff810a8428
#24 [ffff88272f5aff50] ret_from_fork at ffffffff81745242
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/loop.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 3036883fc9f8..ab7ca5989097 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -885,7 +885,7 @@ static void loop_unprepare_queue(struct loop_device *lo) static int loop_kthread_worker_fn(void *worker_ptr) { - current->flags |= PF_LESS_THROTTLE; + current->flags |= PF_LESS_THROTTLE | PF_MEMALLOC_NOIO; return kthread_worker_fn(worker_ptr); } |