Re: 4.5-rc1 multipath regression

From: Mike Snitzer <snitzer@redhat.com>
To: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: device-mapper development <dm-devel@redhat.com>
Subject: Re: 4.5-rc1 multipath regression
Date: Fri, 29 Jan 2016 19:06:58 -0500	[thread overview]
Message-ID: <20160130000657.GA14034@redhat.com> (raw)
In-Reply-To: <56ABB279.5020609@sandisk.com>

On Fri, Jan 29 2016 at  1:42pm -0500,
Bart Van Assche <bart.vanassche@sandisk.com> wrote:

> On 01/28/2016 03:39 PM, Bart Van Assche wrote:
> > There is a regression in the 4.5-rc1 kernel with regard to multipath
> > setup. On my SRP I usually use for these tests after a few minutes a
> > kernel crash occurs and the console freezes. A screenshot has been attached.
> 
> (replying to my own e-mail)

Not sure where you sent your first email.. not seeing it on dm-devel
archives.

So I don't have the original screenshot you attached.

The 4.5 merge window didn't see any changes to DM mpath or DM core.  So
any regression is very likely outside DM and rooted in SRP or whatever
other dependencies your setup relies on.

Mike

> Before that crash was triggered, the following appeared in the system log, a
> message I had not yet seen during tests with previous kernel versions:
> 
> INFO: task multipathd:3889 blocked for more than 120 seconds.
>      Tainted: G            E   4.5.0-rc1+ #2
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> multipathd      D ffff88045266b828     0  3889      1 0x00000000
> ffff88045266b828 ffffffff81a0f500 ffff8804254d9f80 ffffffff82145850
> ffffffff810a518d ffffffff82132890 ffff8804254dabc8 ffff8804254d9f80
> 0000000000000002 ffff880400000001 0000000000000002 ffff880400000000
> Call Trace:
> [<ffffffff8152ea42>] schedule+0x42/0xb0
> [<ffffffff81532c9f>] schedule_timeout+0x17f/0x1d0
> [<ffffffff8152fae5>] wait_for_completion+0xe5/0x120
> [<ffffffff81070736>] flush_workqueue+0x256/0x6e0
> [<ffffffffa0352804>] flush_multipath_work+0x34/0x80 [dm_multipath]
> [<ffffffffa035287f>] multipath_postsuspend+0x2f/0x50 [dm_multipath]
> [<ffffffffa000580b>] suspend_targets+0x3b/0x90 [dm_mod]
> [<ffffffffa00058b3>] dm_table_postsuspend_targets+0x13/0x20 [dm_mod]
> [<ffffffffa00042f4>] dm_suspend+0xf4/0x130 [dm_mod]
> [<ffffffffa0009d5f>] do_resume+0x15f/0x1d0 [dm_mod]
> [<ffffffffa0009e5a>] dev_suspend+0x8a/0xc0 [dm_mod]
> [<ffffffffa000ad3c>] ctl_ioctl+0x18c/0x280 [dm_mod]
> [<ffffffffa000ae3e>] dm_ctl_ioctl+0xe/0x20 [dm_mod]
> [<ffffffff81196903>] vfs_ioctl+0x13/0x30
> [<ffffffff811972e2>] do_vfs_ioctl+0x82/0x420
> [<ffffffff811976ce>] SyS_ioctl+0x4e/0x80
> [<ffffffff81534197>] entry_SYSCALL_64_fastpath+0x12/0x6f
> 2 locks held by multipathd/3889:
> #0:  (&md->suspend_lock/1){+.+...}, at: [<ffffffffa0004232>] dm_suspend+0x32/0x130 [dm_mod]
> #1:  (&m->work_mutex){+.+.+.}, at: [<ffffffffa0352877>] multipath_postsuspend+0x27/0x50 [dm_multipath]
> 
> 
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