From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Mikulas Patocka <mpatocka@redhat.com>,
Mike Snitzer <snitzer@redhat.com>,
Sasha Levin <sashal@kernel.org>,
linux-raid@vger.kernel.org
Subject: [PATCH AUTOSEL 4.4 1/6] Revert "dm bufio: fix deadlock with loop device"
Date: Thu, 29 Aug 2019 06:51:05 -0400 [thread overview]
Message-ID: <20190829105110.2748-1-sashal@kernel.org> (raw)
From: Mikulas Patocka <mpatocka@redhat.com>
[ Upstream commit cf3591ef832915892f2499b7e54b51d4c578b28c ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/dm-bufio.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 8a6e7646e1c98..b1d5fa0bc8f7b 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1561,7 +1561,9 @@ 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);
--
2.20.1
next reply other threads:[~2019-08-29 10:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 10:51 Sasha Levin [this message]
2019-08-29 10:51 ` [PATCH AUTOSEL 4.4 2/6] userfaultfd_release: always remove uffd flags and clear vm_userfaultfd_ctx Sasha Levin
2019-08-29 10:51 ` [PATCH AUTOSEL 4.4 3/6] mac80211: fix possible sta leak Sasha Levin
2019-08-29 10:51 ` [PATCH AUTOSEL 4.4 4/6] scripts/decode_stacktrace: match basepath using shell prefix operator, not regex Sasha Levin
2019-08-29 10:51 ` [PATCH AUTOSEL 4.4 5/6] KVM: arm/arm64: Only skip MMIO insn once Sasha Levin
2019-08-29 10:51 ` [PATCH AUTOSEL 4.4 6/6] clk: s2mps11: Add used attribute to s2mps11_dt_match Sasha Levin
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