From: Mike Snitzer <snitzer@redhat.com>
To: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
device-mapper development <dm-devel@redhat.com>,
"hch@lst.de" <hch@lst.de>
Subject: Re: [PATCH 8/9] dm: Fix two race conditions related to stopping and starting queues
Date: Thu, 1 Sep 2016 16:48:06 -0400 [thread overview]
Message-ID: <20160901204806.GA12742@redhat.com> (raw)
In-Reply-To: <889bdb89-a16b-927a-adf0-fa04418a0c06@sandisk.com>
On Thu, Sep 01 2016 at 4:39pm -0400,
Bart Van Assche <bart.vanassche@sandisk.com> wrote:
> On 09/01/2016 01:33 PM, Mike Snitzer wrote:
> >I'm able to easily reproduce this 100% cpu usage using mptest's
> >test_02_sdev_delete.
> >
> >'dmsetup suspend --nolockfs --noflush mp' hangs, seems rooted in your
> >use of blk_mq_freeze_queue():
> >
> >[ 298.136930] dmsetup D ffff880142cb3b70 0 9478 9414 0x00000080
> >[ 298.144831] ffff880142cb3b70 ffff880142cb3b28 ffff880330d6cb00 ffff88032d0022f8
> >[ 298.153132] ffff880142cb4000 ffff88032d0022f8 ffff88032b161800 0000000000000001
> >[ 298.161438] 0000000000000001 ffff880142cb3b88 ffffffff816c06e5 ffff88032d001aa0
> >[ 298.169740] Call Trace:
> >[ 298.172473] [<ffffffff816c06e5>] schedule+0x35/0x80
> >[ 298.178019] [<ffffffff8131b937>] blk_mq_freeze_queue_wait+0x57/0xc0
> >[ 298.185116] [<ffffffff810c58c0>] ? prepare_to_wait_event+0xf0/0xf0
> >[ 298.192117] [<ffffffff8131d92a>] blk_mq_freeze_queue+0x1a/0x20
> >[ 298.198734] [<ffffffffa000e910>] dm_stop_queue+0x50/0xc0 [dm_mod]
> >[ 298.205644] [<ffffffffa0001824>] __dm_suspend+0x134/0x1f0 [dm_mod]
> >[ 298.212649] [<ffffffffa00035b8>] dm_suspend+0xb8/0xd0 [dm_mod]
> >[ 298.219270] [<ffffffffa000882e>] dev_suspend+0x18e/0x240 [dm_mod]
> >[ 298.226175] [<ffffffffa00086a0>] ? table_load+0x380/0x380 [dm_mod]
> >[ 298.233180] [<ffffffffa0009027>] ctl_ioctl+0x1e7/0x4d0 [dm_mod]
> >[ 298.239890] [<ffffffff81197f00>] ? lru_cache_add_active_or_unevictable+0x10/0xb0
> >[ 298.248253] [<ffffffffa0009323>] dm_ctl_ioctl+0x13/0x20 [dm_mod]
> >[ 298.255049] [<ffffffff81227937>] do_vfs_ioctl+0xa7/0x5d0
> >[ 298.261081] [<ffffffff8112787f>] ? __audit_syscall_entry+0xaf/0x100
> >[ 298.268178] [<ffffffff8100365d>] ? syscall_trace_enter+0x1dd/0x2c0
> >[ 298.275179] [<ffffffff81227ed9>] SyS_ioctl+0x79/0x90
> >[ 298.280821] [<ffffffff81003a47>] do_syscall_64+0x67/0x160
> >[ 298.286950] [<ffffffff816c4921>] entry_SYSCALL64_slow_path+0x25/0x25
> >
>
> Hello Mike,
>
> In your dm-4.9 branch I see that you call blk_mq_freeze_queue()
> while holding the block layer queue lock. Please don't do this.
> blk_mq_freeze_queue() can sleep and as you know calling a sleeping
> function while holding a spinlock is not allowed.
Yeah, I since fixed that. Doesn't change the fact that your use of
blk_mq_freeze_queue() causes the 100% cpu usage.
next prev parent reply other threads:[~2016-09-01 20:48 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-31 22:14 [PATCH 0/9] dm patches for kernel v4.9 Bart Van Assche
2016-08-31 22:15 ` [PATCH 1/9] blk-mq: Introduce blk_mq_queue_stopped() Bart Van Assche
2016-08-31 22:16 ` [PATCH 2/9] dm: Rename a function argument Bart Van Assche
2016-09-01 3:29 ` Mike Snitzer
2016-09-01 14:17 ` Bart Van Assche
2016-08-31 22:16 ` [PATCH 3/9] dm: Introduce signal_pending_state() Bart Van Assche
2016-08-31 22:16 ` [PATCH 4/9] dm: Convert wait loops Bart Van Assche
2016-08-31 22:17 ` [PATCH 5/9] dm: Add two lockdep_assert_held() statements Bart Van Assche
2016-08-31 22:17 ` [PATCH 6/9] dm: Simplify dm_old_stop_queue() Bart Van Assche
2016-08-31 22:17 ` [PATCH 7/9] dm: Mark block layer queue dead before destroying the dm device Bart Van Assche
2016-08-31 22:18 ` [PATCH 8/9] dm: Fix two race conditions related to stopping and starting queues Bart Van Assche
2016-09-01 3:13 ` Mike Snitzer
2016-09-01 14:23 ` Bart Van Assche
2016-09-01 15:05 ` Mike Snitzer
2016-09-01 15:31 ` Bart Van Assche
2016-09-01 15:50 ` Mike Snitzer
2016-09-01 16:12 ` Mike Snitzer
2016-09-01 17:59 ` Bart Van Assche
2016-09-01 19:05 ` Mike Snitzer
2016-09-01 19:35 ` Mike Snitzer
2016-09-01 20:15 ` Bart Van Assche
2016-09-01 20:33 ` Mike Snitzer
2016-09-01 20:39 ` Bart Van Assche
2016-09-01 20:48 ` Mike Snitzer [this message]
2016-09-01 20:52 ` Bart Van Assche
2016-09-01 21:17 ` Mike Snitzer
2016-09-01 22:18 ` Mike Snitzer
2016-09-01 22:22 ` Bart Van Assche
2016-09-01 22:26 ` Mike Snitzer
2016-09-01 23:17 ` Bart Van Assche
2016-09-01 23:47 ` Mike Snitzer
2016-09-02 0:03 ` Bart Van Assche
2016-09-02 15:12 ` Mike Snitzer
2016-09-02 16:10 ` should blk-mq halt requeue processing while queue is frozen? [was: Re: [PATCH 8/9] dm: Fix two race conditions related to stopping and starting queues] Mike Snitzer
2016-09-02 22:42 ` [dm-devel] should blk-mq halt requeue processing while queue is frozen? Bart Van Assche
2016-09-03 0:34 ` Mike Snitzer
2016-09-07 16:41 ` Mike Snitzer
2016-09-13 8:01 ` [dm-devel] " Bart Van Assche
2016-09-13 14:36 ` Mike Snitzer
2016-08-31 22:18 ` [PATCH 9/9] dm path selector: Avoid that device removal triggers an infinite loop Bart Van Assche
2016-09-01 2:49 ` Mike Snitzer
2016-09-01 14:14 ` Bart Van Assche
2016-09-01 15:06 ` Mike Snitzer
2016-09-01 15:22 ` Bart Van Assche
2016-09-01 15:26 ` Mike Snitzer
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