Re: [rfc][patch] Avoid taking global tasklist_lock for single threadedprocess at getrusage()

[Oleg Nesterov <oleg@tv-sign.ru>]

Ravikiran G Thirumalai wrote:
>
> __exit_signal
>         cleanup_sighand(tsk);
>                 kmem_cache_free(sighand)
>         spin_unlock(sighand->lock)
> 
> It looked suspicious to me until I realised sighand cache now had
> SLAB_DESTROY_BY_RCU. Can we please add comments (at cleanup_sighand or
> __exit_signal) to make it a bit clearer for people like me :)

Yes, this is really confusing, see also
	http://marc.theaimsgroup.com/?l=linux-kernel&m=114089590923893
I'll send a cleanup patch soon.

> How is the following patch to avoid tasklist lock completely at getrusage?

I think this patch is correct, thanks.

Oleg.
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