linux-kernel - Re: INFO: possible circular locking dependency detected

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Message-ID: <4533980C.10403@yahoo.com.au>
Date:	Tue, 17 Oct 2006 00:32:44 +1000
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	"alpha @ steudten Engineering" <alpha@...udten.com>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: INFO: possible circular locking dependency detected

alpha @ steudten Engineering wrote:
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.18-1.2189self #1
> -------------------------------------------------------
> kswapd0/186 is trying to acquire lock:
>  (&inode->i_mutex){--..}, at: [<c0326e32>] mutex_lock+0x21/0x24
> 
> but task is already holding lock:
>  (iprune_mutex){--..}, at: [<c0326e32>] mutex_lock+0x21/0x24
> 
> which lock already depends on the new lock.

Thanks. __grab_cache_page wants to clear __GFP_FS, because it is
holding the i_mutex so we don't want to reenter the filesystem in
page reclaim.

This would be an easy two liner, except those funny page_cache_alloc
routines which take a mapping rather than a gfp_t argument :P

Anyway, I'll get around to writing the real patch and queue it up
with my other buffered write deadlock fixes. It should be fairly
unlikely to cause you a deadlock. You could give this quick patch a
try, though. Does it fix your problem?

-- 
SUSE Labs, Novell Inc.

View attachment "mm-write-deadlock.patch" of type "text/plain" (1443 bytes)