linux-kernel - Re: [2.6.32-rc4] + EXT4 corruption

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Message-ID: <4AD481A4.6040706@mit.edu>
Date:	Tue, 13 Oct 2009 09:33:24 -0400
From:	Andy Lutomirski <luto@....edu>
To:	Theodore Tso <tytso@....edu>, Shawn Starr <shawn.starr@...ers.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [2.6.32-rc4] + EXT4 corruption

Theodore Tso wrote:
> On Mon, Oct 12, 2009 at 10:07:49PM -0400, Shawn Starr wrote:
>> Hello everyone, 
>>
>> I somehow managed to corrupt some of my filesystem.
>>
>> What I did was this:
>>
>> in /etc/modprobe.d/alsa-base.conf (Kubuntu)
>>
>> I added:
>>
>> install snd-aloop /sbin/modprobe snd-aloop
>>
>> Saved it, then ran, modprobe snd-aloop, the system started spawning
>> many copies of modprobe, then machine started going though a swap
>> storm, could not reboot safely, hit power button on laptop. When the
>> system came back up, EXT4 greeted me with severe errors on some
>> opened files. It did repair filesystem however. It corrupted some
>> configuration files that were open at the time of the shutdown.
>>
>> I'm guessing no matter how much you attempt to replay a journal you
>> still can get corruption such as this?
> 
> You shouldn't get any file system corruption after replaying a
> journal.  I'm trying to get an easily reproducible test case for this.
> Can you give me more information about where your root filesystem is
> located.  Is it using LVM?  dm-crypt?  Can you reliably reproducible
> the file system corruption?

I triggered what might have been the same bug awhile ago on 2.6.32-rc2 
or so (with your patch to fix a writepages OOPS applied, I think).  I 
crashed my system by doing something dumb with the i915 driver, and, 
after power cycling, I had all kinds of corrupt inodes.  e2fsck fixed it 
  just fine and only lost /etc/ld.so.cache.

This was LVM over dm-crypt on a partition on AHCI on a real (non-SSD) 
hard disk.

--Andy

> 
> 						- Ted
> 
> 
> 					

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