linux-kernel - Re: pdflush stuck in D state with v2.6.24-rc1-192-gef49c32

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Message-Id: <E1ImlvH-0003YH-Qf@localhost>
Date:	Tue, 30 Oct 2007 15:54:03 +0800
From:	Fengguang Wu <wfg@...l.ustc.edu.cn>
To:	Florin Iucha <florin@...ha.net>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Trond Myklebust <trond.myklebust@....uio.no>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: pdflush stuck in D state with v2.6.24-rc1-192-gef49c32

On Sun, Oct 28, 2007 at 10:24:29AM -0500, Florin Iucha wrote:
[...]
>    [ 3687.824468] 
>    [ 3687.824470] pdflush       D ffffffff805787c0     0   248      2
>    [ 3687.824473]  ffff810006001d90 0000000000000046 0000000000000000 0000000000000286
>    [ 3687.824476]  ffff8100057fc770 ffff810003062000 ffff8100057fc978 0000000106001da0
>    [ 3687.824480]  0000000000000003 ffffffff8023b1b2 0000000000000000 0000000000000000
>    [ 3687.824483] Call Trace:
>    [ 3687.824488]  [<ffffffff8023b1b2>] __mod_timer+0xb8/0xca
>    [ 3687.824492]  [<ffffffff8055c87a>] schedule_timeout+0x8d/0xb4
>    [ 3687.824496]  [<ffffffff8023ad6c>] process_timeout+0x0/0xb
>    [ 3687.824499]  [<ffffffff8055c79a>] io_schedule_timeout+0x28/0x33
>    [ 3687.824503]  [<ffffffff8026bb24>] congestion_wait+0x6b/0x87
>    [ 3687.824506]  [<ffffffff80245983>] autoremove_wake_function+0x0/0x38
>    [ 3687.824510]  [<ffffffff8029e684>] writeback_inodes+0xcd/0xd5
>    [ 3687.824514]  [<ffffffff80266dc4>] wb_kupdate+0xbb/0x10d
>    [ 3687.824518]  [<ffffffff80267165>] pdflush+0x0/0x1c3
>    [ 3687.824520]  [<ffffffff8026727d>] pdflush+0x118/0x1c3
>    [ 3687.824523]  [<ffffffff80266d09>] wb_kupdate+0x0/0x10d
>    [ 3687.824527]  [<ffffffff80245876>] kthread+0x49/0x77
>    [ 3687.824530]  [<ffffffff8020c598>] child_rip+0xa/0x12
>    [ 3687.824535]  [<ffffffff8024582d>] kthread+0x0/0x77
>    [ 3687.824538]  [<ffffffff8020c58e>] child_rip+0x0/0x12
>    [ 3687.824540] 
> 
> What could cause this?  I use NFS4 to automount the home directories
> from a Solaris10 server, and this box found a few bugs in the NFS4
> code (fixed in the 2.6.22 kernel).
> 
> I'll try running with 2.6.23 again for a few days, to see if I get the
> pdflush stuck.  Any other ideas?

It could be triggered by the more aggressive writeback behavior - the
new code will keep on retrying as long as there are dirty inodes pending.

Florin, would you try the attached patches against 2.6.24-git?
They may generate big traffic of printk messages, but will help
debug the problem.

Thank you,
Fengguang

View attachment "writeback-debug.patch" of type "text/x-diff" (1926 bytes)

View attachment "requeue_io-debug.patch" of type "text/x-diff" (1141 bytes)