From: Mark Lord <kernel@teksavvy.com>
To: Ted Ts'o <tytso@mit.edu>,
Linux Kernel <linux-kernel@vger.kernel.org>,
linux-ext4@vger.kernel.org
Subject: Re: ext4 crash on 2.6.37: NULL ptr in ext4_discard_preallocations
Date: Sun, 20 Feb 2011 00:05:27 -0500 [thread overview]
Message-ID: <4D60A117.8090604@teksavvy.com> (raw)
In-Reply-To: <4D609E87.5000903@teksavvy.com>
On 11-02-19 11:54 PM, Mark Lord wrote:
> On 11-02-19 07:05 PM, Ted Ts'o wrote:
>> On Sat, Feb 19, 2011 at 05:37:20PM -0500, Mark Lord wrote:
>>> 32-bit x86 system, 2.6.37 SMP kernel, Core2duo, 3.3GB RAM, no swap.
>>>
>>> The system just suddenly switched to fbconsole and dumped a traceback.
>>> Here's the screen-shot photo: http://rtr.ca/ext4_crash.jpg
>>>
>>> Is this a known bug that got fixed in 2.6.37.1 ?
>>
>> No, this looks like a new one.
>>
>> And I can't make the Code: line make sense. Can you send me the
>> fs/ext4/mballoc.s file after running the command "make
>> fs/ext4/mballoc.s" in your build tree where you built this kernel?
>
> Sent. And here's an extract:
>
> .globl ext4_discard_preallocations
> .type ext4_discard_preallocations, @function
> ext4_discard_preallocations:
> pushl %ebp #
> pushl %edi #
> leal -136(%eax), %edi #, ei
> pushl %esi #
> pushl %ebx #
> subl $80, %esp #,
> movl 172(%eax), %esi # <variable>.i_sb, sb
> movl $0, 76(%esp) #, group
> movzwl 122(%eax), %edx # <variable>.i_mode, tmp85
> andl $61440, %edx #, tmp85
> cmpl $32768, %edx #, tmp85
> jne .L875 #,
> leal 68(%esp), %edx #, tmp86
> leal 380(%eax), %ebx #, D.45176
> movl %edx, 68(%esp) # tmp86, list.next
> addl $372, %eax #,
> movl %edx, 72(%esp) # tmp86, list.prev
> movl %eax, 28(%esp) #, %sfp
> .L876:
> movl %ebx, %eax # D.45176,
> call _raw_spin_lock #
> jmp .L861 #
> .L867:
> cmpl %ebx, 60(%ebp) # D.45176, <variable>.pa_obj_lock
> je .L862 #,
> #APP
> # 3810 "fs/ext4/mballoc.c" 1
> 1: ud2
>
> I wonder if the 003c offset is that "cmpl %ebx, 60(%ebp)" line?
I suppose it must be, as there's no other 0x3c offset in that function.
Which means it's probably this line that's crashing:
BUG_ON(pa->pa_obj_lock != &ei->i_prealloc_lock);
...which could only happen if "pa" was NULL there.
I wonder how that happened ?
next prev parent reply other threads:[~2011-02-20 5:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-19 22:37 ext4 crash on 2.6.37: NULL ptr in ext4_discard_preallocations Mark Lord
2011-02-20 0:05 ` Ted Ts'o
2011-02-20 4:54 ` Mark Lord
2011-02-20 5:05 ` Mark Lord [this message]
2011-02-20 6:15 ` Ted Ts'o
2011-02-20 13:55 ` Mark Lord
2011-02-20 14:39 ` Mark Lord
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