linux-kernel - Re: 2.6.27 BUG at fs/inode.c:263 with ext4

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Date:	Thu, 15 Jan 2009 00:02:19 +0000
From:	Alex Buell <alex.buell@...ted.org.uk>
To:	Theodore Tso <tytso@....EDU>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.27 BUG at fs/inode.c:263 with ext4

On Wed, 14 Jan 2009 16:54:30 -0500, I waved a wand and this message
magically appears in front of Theodore Tso:

> On Wed, Jan 14, 2009 at 09:01:43PM +0000, Alex Buell wrote:
> > I've been testing ext4 with some spare disks, tonight I created an
> > ext4fs on a USB 60GB hard disk, and backed up my /home partition
> > onto it with rsync.
> > 
> > After umounting the device, and switching off the USB connection I
> > got the following in my /var/log/messages.
> > 
> > What would this suggest? I'd be happy to supply further information
> > if required.
> 
> Can you reproduce this error?  

I've just tried with another PATA hard disk over USB. Although there wasn't a BUG, I noticed this in the logs: 

Jan 14 23:04:34 lithium usb 1-3.3: USB disconnect, address 14
Jan 14 23:04:34 lithium udevd-event[17345]: unlink_secure: chmod(/dev/bus/usb/001/014, 0000) failed: No such file or directory

Which makes me wonder if you might be right in that it might be a problem with udevd.

> ... and it's apparently coming from udevd when it deletes the device
> node from /dev, which looks like is a tempfs filesystem.  That would
> explain the call stack, which shows that clear_inode() was apparently
> called from shmem_delete_inode():
> 
> > Jan 14 20:50:00 lithium [<c0157c55>] shmem_delete_inode+0x0/0xae
> > Jan 14 20:50:00 lithium [<c016b6e3>] generic_delete_inode+0x91/0xf9
> > Jan 14 20:50:00 lithium [<c016ae1d>] iput+0x48/0x4a
> > Jan 14 20:50:00 lithium [<c0163a44>] do_unlinkat+0xb0/0x11f
> > Jan 14 20:50:00 lithium [<c0112ace>] do_page_fault+0x23c/0x54a
> > Jan 14 20:50:00 lithium [<c0102cb1>] sysenter_do_call+0x12/0x25
> 
> That would imply that there were pages from the block device still in
> the page cache, which I suspect means they were left over from mke2fs
> or fsck, or some other program directly accessing the block device
> directly.  I wonder if this BUG can be triggered if a process has an
> open file descriptor on the device at the time when it's powered off,
> or pulled from the system?

After that message in the /var/log/messages file, I tried a couple of times, could not reproduce anything at all. I think that this probably is a udevd problem. But I do add that before I used the disks, I did run mkfs.ext4 to create the filesystem, and also a few fsck.ext4 runs, all of which completed without problems. 

I am currently running another rsync task with the disk at the moment. 
-- 
http://www.munted.org.uk

Fearsome grindings.
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