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Date: Tue, 2 Oct 2012 13:32:53 -0700 (PDT)
From: Hugh Dickins <hughd@google.com>
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To: Shuah Khan <shuah.khan@hp.com>
cc: LKML <linux-kernel@vger.kernel.org>, shuahkhan@gmail.com
Subject: Re: kernel null pointer dereference at kmem_cache_alloc+0x5b/0x140
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On Tue, 2 Oct 2012, Shuah Khan wrote:
> I started seeing the following null pointer dereference on
> a linux-next sept 21 git and still seeing it on linux-next 
> Sep 27th git.
> 
> Can be reproduced easily. I have been able to reproduce every
> time I do a complete build of a kernel on fresh checkout or
> touch a header file that forces full build.
> 
> I didn't get a chance to investigate this yet, thought I would
> share just in case others have seen it.
> 
> [11478.881196] BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
> [11478.881245] IP: [<ffffffff811742bb>] kmem_cache_alloc+0x5b/0x140
> [11478.881277] PGD 74386067 PUD 5dfab067 PMD 0 
> [11478.881302] Oops: 0000 [#2] SMP 
> [11478.881705] CPU 0 
> [11478.881717] Pid: 6399, comm: ld Tainted: G      D      3.6.0-rc7-next-20120927+ #1 Hewlett-Packard HP EliteBook 6930p/30DC
> [11478.884005] Process ld (pid: 6399, threadinfo ffff88005dec0000, task ffff88007bf244a0)
> [11478.884005] Call Trace:
> [11478.884005]  [<ffffffff8125dab1>] ext4_es_insert_extent+0x1e1/0x2f0

ext4_es_insert_extent again: probably fixed by the same patch as I just
sent in your other kernel NULL pointer dereference thread.

Hugh
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