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| author | Mikulas Patocka <mpatocka@redhat.com> | 2019-08-08 12:40:04 +0300 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2019-08-15 22:57:39 +0300 |
| commit | cf3591ef832915892f2499b7e54b51d4c578b28c (patch) | |
| tree | f791b1026bd179abc877f63ebf9e6069b41f8ebe | |
| parent | d45331b00ddb179e291766617259261c112db872 (diff) | |
| download | linux-cf3591ef832915892f2499b7e54b51d4c578b28c.tar.xz | |
Revert "dm bufio: fix deadlock with loop device"
Revert the commit bd293d071ffe65e645b4d8104f9d8fe15ea13862. The proper
fix has been made available with commit d0a255e795ab ("loop: set
PF_MEMALLOC_NOIO for the worker thread").
Note that the fix offered by commit bd293d071ffe doesn't really prevent
the deadlock from occuring - if we look at the stacktrace reported by
Junxiao Bi, we see that it hangs in bit_wait_io and not on the mutex -
i.e. it has already successfully taken the mutex. Changing the mutex
from mutex_lock to mutex_trylock won't help with deadlocks that happen
afterwards.
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
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Fixes: bd293d071ffe ("dm bufio: fix deadlock with loop device")
Depends-on: d0a255e795ab ("loop: set PF_MEMALLOC_NOIO for the worker thread")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
| -rw-r--r-- | drivers/md/dm-bufio.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index b6b5acc92ca2..2a48ea3f1b30 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1599,7 +1599,9 @@ dm_bufio_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) unsigned long freed; c = container_of(shrink, struct dm_bufio_client, shrinker); - if (!dm_bufio_trylock(c)) + if (sc->gfp_mask & __GFP_FS) + dm_bufio_lock(c); + else if (!dm_bufio_trylock(c)) return SHRINK_STOP; freed = __scan(c, sc->nr_to_scan, sc->gfp_mask); |