Oleg Nesterov wrote:
> On 01/17, Daniel Hokka Zakrisson wrote:
>>>> Call Trace:
>>>> [<c03be6f0>] _spin_lock_irqsave+0x20/0x90
>>>> [<c01f6115>] lockd_down+0x125/0x190
>>>> [<c01d26bd>] nfs_free_server+0x6d/0xd0
>>>> [<c01d8e9c>] nfs_kill_super+0xc/0x20
>>>> [<c0161c5d>] deactivate_super+0x7d/0xa0
>>>> [<c0175e0e>] release_mounts+0x6e/0x80
>>>> [<c0175e86>] __put_mnt_ns+0x66/0x80
>>>> [<c0132b3e>] free_nsproxy+0x5e/0x60
>>>> [<c011f021>] do_exit+0x791/0x810
>>>> [<c011f0c6>] do_group_exit+0x26/0x70
>>>> [<c0103142>] sysenter_past_esp+0x5f/0x85
>>>> [<c03b0033>] rpc_wake_up+0x3/0x70
>> It was the only semi-plausible explanation I could come up with. I added a
>> printk in do_exit right before exit_task_namespaces, where sighand was
>> still set, and one right before the spin_lock_irq in lockd_down, where it
>> had suddenly been set to NULL.
>
> I can't reproduce the problem, but
I did on a 2.6.20-rc4-mm1.
> do_exit:
> exit_notify(tsk);
> exit_task_namespaces(tsk);
>
> the task could be reaped by its parent in between.
indeed. while it goes spleeping in lockd_down() just before it does
spin_lock_irq(¤t->sighand->siglock);
current->sighand is valid before interruptible_sleep_on_timeout() and
not after.
> We should not use ->signal/->sighand after exit_notify().
>
> Can we move exit_task_namespaces() up?
yes but I moved it down because it invalidates ->nsproxy ...
C.
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