From: Mikulas Patocka <mpatocka@redhat.com>
To: Jens Axboe <axboe@kernel.dk>, Matthew Wilcox <willy@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Mike Snitzer <msnitzer@redhat.com>,
junxiao.bi@oracle.com, dm-devel@redhat.com,
Alasdair Kergon <agk@redhat.com>,
honglei.wang@oracle.com, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-block@vger.kernel.org
Subject: [PATCH] loop: set PF_MEMALLOC_NOIO for the worker thread
Date: Thu, 8 Aug 2019 11:17:01 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.1908081113540.18950@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <20190808135329.GG5482@bombadil.infradead.org>
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
---
drivers/block/loop.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6/drivers/block/loop.c
===================================================================
--- linux-2.6.orig/drivers/block/loop.c 2019-08-08 17:02:50.000000000 +0200
+++ linux-2.6/drivers/block/loop.c 2019-08-08 17:08:14.000000000 +0200
@@ -885,7 +885,7 @@ static void loop_unprepare_queue(struct
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);
}
next prev parent reply other threads:[~2019-08-08 15:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-08 9:50 [PATCH] direct-io: use GFP_NOIO to avoid deadlock Mikulas Patocka
2019-08-08 13:53 ` Matthew Wilcox
2019-08-08 15:13 ` Mikulas Patocka
2019-08-08 15:17 ` Mikulas Patocka [this message]
2019-08-08 16:12 ` [PATCH] loop: set PF_MEMALLOC_NOIO for the worker thread Jens Axboe
2019-08-08 14:39 ` [PATCH] direct-io: use GFP_NOIO to avoid deadlock Junxiao Bi
2019-08-09 1:34 ` Dave Chinner
2019-08-09 11:30 ` Mikulas Patocka
2019-08-09 21:57 ` Dave Chinner
2019-08-13 16:35 ` Mikulas Patocka
2019-08-14 10:43 ` Dave Chinner
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