Re: 2.6.39-rc0: umount tmpfs hangs

[Alexander Beregalov]

On 21 March 2011 06:39, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Mar 21, 2011 at 05:24:08AM +0300, Alexander Beregalov wrote:
>> Hi
>>
>> kernel is 2.6.38-06507-ga952baa
>>
>> /etc/init.d/swap stop
>> runs
>> umount -a -t tmpfs
>>
>> which is hangs at
>>
>> $cat /proc/4453/stack
>> [<c1066332>] rcu_barrier_sched+0x32/0x40
>> [<c109fdca>] deactivate_locked_super+0x3a/0x60
>> [<c10a05f6>] deactivate_super+0x46/0x60
>> [<c10b6f2a>] mntput_no_expire+0x5a/0x90
>> [<c10b7a6d>] sys_umount+0x5d/0x300
>> [<c10b7d29>] sys_oldumount+0x19/0x20
>> [<c136eb50>] sysenter_do_call+0x12/0x36
>> [<ffffffff>] 0xffffffff
>
> rcu_barrier() hanging for some reason... ÂI really wonder what's going
> on there - missing rcu_read_unlock()? ÂCould you try to reproduce that
> sucker and, if possible, bisect it?

Yes, it's reproducible, but I'm bisecting another issue and have few
more such issues with the current kernel.
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