Re: busy inodes -> ext3 umount crash

From: Jiri Slaby <jirislaby@gmail.com>
To: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	adilger@sun.com, linux-ext4@vger.kernel.org,
	Linux kernel mailing list <linux-kernel@vger.kernel.org>,
	mszeredi@suse.cz
Subject: Re: busy inodes -> ext3 umount crash
Date: Mon, 19 Apr 2010 16:33:24 +0200	[thread overview]
Message-ID: <4BCC69B4.2050308@gmail.com> (raw)
In-Reply-To: <20100419141158.GB5439@quack.suse.cz>

On 04/19/2010 04:11 PM, Jan Kara wrote:
>> I have no idea how to reproduce it :(, but it usually happens when I do
>> shutdown/kexec.
>   If it's the patch I suspect above, then moving one directory over another
> one might trigger the leak which would be later spotted on umount of the
> filesystem. Or maybe to trigger the leak you have to have a process which
> has its CWD in the directory you are going to delete by the rename... not
> sure.

The trigger for busy inodes is as simple as (I=initialization done only
once):
I> # dd if=/dev/zero of=/dev/shm/ext3 bs=1024 count=1 seek=$((100*1024))
I> # mkfs.ext3 -m 0 /dev/shm/ext3
# mount -oloop /dev/shm/ext3 /mnt/c
# umount /mnt/c
# dmesg|tail
VFS: Busy inodes after unmount of loop0. Self-destruct in 5 seconds.
Have a nice day...

(The printk time varies -- this sequence really suffices.)

> So if you can easily reproduce
> the "busy inodes" message then I'd start with debugging that one. Do you
> see it also with vanilla kernels?

I don't know, now I'm going to play with that as I have the trigger ;).
Will be back soon.

thanks,
-- 
js