Re: [PATCH 1/1] aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()

From: Mateusz Guzik
Date: Tue Apr 29 2014 - 19:05:19 EST


On Tue, Apr 29, 2014 at 05:22:22PM -0400, Benjamin LaHaise wrote:
> On Tue, Apr 29, 2014 at 04:42:17PM -0400, Benjamin LaHaise wrote:
> > > Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
> >
> > Your patch does not apply because it is whitespace damaged. Please resend
> > and verify that it applies with 'git am'.
>
> Whoops, it's not whitespace damange, but rather that it doesn't apply with
> the other changes that are queued up in the aio-next tree. You can find a
> copy of that tree at git://git.kvack.org/~bcrl/aio-next.git . The change
> that conflicts is an additional parameter to kill_ioctx().

While here is there any reason for:
rcu_assign_pointer(mm->ioctx_table, NULL);

Nothing looks at this pointer afterwards and mm is about to be freed.

I thought it would be used to sanity check that everything was cleared
before freeing, but that is nod one and not every pointer is nullified
anyway.

--
Mateusz Guzik
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