Subject: Re: 2.6.23.1 NULL pointer dereference in NFS
From: Trond Myklebust <trond.myklebust@fys.uio.no>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <20071106204808.GB18743@Krystal>
References: <20071106204808.GB18743@Krystal>
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Date: Wed, 07 Nov 2007 08:32:08 -0500
Message-Id: <1194442328.7456.5.camel@heimdal.trondhjem.org>
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On Tue, 2007-11-06 at 15:48 -0500, Mathieu Desnoyers wrote:
> Hi,
> 
> I just ran through this OOPS when I was doing a dpkg dist-upgrade on my
> Pentium III. Any idea what could have caused this ?
> 
> (by the way, this computer is generally slow since I upgraded to
> 2.6.23.1. It could be a related symptom...)
> 
> BUG: unable to handle kernel NULL pointer dereference at virtual address 00000000
>  printing eip:
> c54a53cf
> *pde = 00000000
> Oops: 0002 [#1]
> PREEMPT 
> Modules linked in: mga_vid fuse rt2570 iptable_filter ip_tables x_tables tun mga drm uhci_hcd 3c59x mii via_agp thermal usbcore button agpgart processor
> CPU:    0
>    Not tainted VLI
> EFLAGS: 00210202   (2.6.23.1 #1)
> EIP is at 0xc54a53cf
> eax: c54a5344   ebx: c54a5344   ecx: 00000000   edx: c54a5378
> esi: 00000000   edi: c54a53ac   ebp: c54a5474   esp: dfedbc34
> ds: 007b   es: 007b   fs: 0000  gs: 0033  ss: 0068
> Process xmms (pid: 1337, ti=dfeda000 task=e0602000 task.ti=dfeda000)
> Stack: c041dcc8 00000001 c54a5344 c54a54b8 c54a5344 c54a5344 c54a54b8 e75b6c00 
>        c01f364e 00000000 00000000 c54a5340 c54a54b8 dfedbd54 c01f37c0 00002000 
>        00000000 00002000 dfedbd54 c136bb20 00003000 c01f19b2 00002000 00000000 
> Call Trace:
> __rpc_execute+0x5b/0x21f
> nfs_execute_read+0x30/0x3f
> nfs_pagein_one+0x99/0xd0
> nfs_pageio_doio+0x2e/0x54
> nfs_pageio_add_request+0x98/0xa9
> readpage_async_filler+0x117/0x134
> readpage_async_filler+0x0/0x134
> read_cache_pages+0x6a/0xb4
> nfs_readpages+0x124/0x173
> nfs_pagein_one+0x0/0xd0
> nfs_readpages+0x0/0x173
> __do_page_cache_readahead+0x19b/0x260
> update_curr+0x102/0x12c
> ondemand_readahead+0x48/0xee
> page_cache_sync_readahead+0x2a/0x2f
> do_generic_mapping_read+0xd8/0x3d0
> __check_preempt_curr_fair+0x4f/0x7c
> generic_file_aio_read+0x152/0x181
> file_read_actor+0x0/0xd7
> do_sync_read+0x0/0x109
> do_sync_read+0xc6/0x109
> autoremove_wake_function+0x0/0x33
> do_sync_read+0x0/0x109
> vfs_read+0xa6/0x128
> sys_read+0x41/0x67
> syscall_call+0x7/0xb
>  =======================
> Code: a4 53 4a c5 a4 53 4a c5 c1 cf 50 d7 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 1e 06 00 00 00 00 00 <00> 1e 06 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 

That is a lot of zeros... Did you perchance compile this kernel over NFS
using kernel 2.6.23 or 2.6.23.1? There is a known writeback bug that
results in that kind of corruption. See

   http://bugzilla.kernel.org/show_bug.cgi?id=9315

Cheers
  Trond


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