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References: <20081127200459.GA25799@redhat.com>
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Date: Mon, 1 Dec 2008 15:17:07 -0800
Message-ID: <604427e00812011517tbf5685fr7263225aaa3adb3f@mail.gmail.com>
Subject: Re: + make-get_user_pages-interruptible.patch added to -mm tree
From: Ying Han <yinghan@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: oleg@redhat.com, menage@google.com, penberg@cs.helsinki.fi,
       nickpiggin@yahoo.com.au, hugh@veritas.com, matthew@wil.cx,
       rientjes@google.com, linux-kernel@vger.kernel.org
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thanks Andrew.


On Mon, Dec 1, 2008 at 3:09 PM, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Mon, 1 Dec 2008 15:00:14 -0800
> Ying Han <yinghan@google.com> wrote:
>
>> On Thu, Nov 27, 2008 at 12:04 PM, Oleg Nesterov <oleg@redhat.com> wrote:
>> > Ying Han wrote:
>> >>
>> >> -static int sigkill_pending(struct task_struct *tsk)
>> >> +int sigkill_pending(struct task_struct *tsk)
>> >>  {
>> >>       return  sigismember(&tsk->pending.signal, SIGKILL) ||
>> >>               sigismember(&tsk->signal->shared_pending.signal, SIGKILL);
>> >> diff -puN mm/memory.c~make-get_user_pages-interruptible mm/memory.c
>> >> --- a/mm/memory.c~make-get_user_pages-interruptible
>> >> +++ a/mm/memory.c
>> >> @@ -1219,12 +1219,12 @@ int __get_user_pages(struct task_struct
>> >>                       struct page *page;
>> >>
>> >>                       /*
>> >> -                      * If tsk is ooming, cut off its access to large memory
>> >> -                      * allocations. It has a pending SIGKILL, but it can't
>> >> -                      * be processed until returning to user space.
>> >> +                      * If we have a pending SIGKILL, don't keep
>> >> +                      * allocating memory.
>> >>                        */
>> >> -                     if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE)))
>> >> -                             return i ? i : -ENOMEM;
>> >> +                     if (unlikely(sigkill_pending(current) ||
>> >> +                                     sigkill_pending(tsk)))
>> >
>> > Please do not export/use sigkill_pending(). It is "private" for ptrace_stop()
>> > (and actually should die imho).
>> >
>> > We have fatal_signal_pending() for that.
>> >
>> > Oleg.
>> >
>
> (top-posting repaired..)
>
>> Thanks Oleg, i looked at the code again and this is a reasonable
>> change. I will make the change on the patch.
>> Andrew,
>>     should i make a patch based on current change or make the same
>> patch as [V6]?
>
> I don't mind either way.  I guess a fresh new patch would simplify
> review for everyone.
>
> Note that fatal_signal_pending() is not an exact replacement for
> sigkill_pending() - fatal_signal_pending() doesn't test the shared
> pending signals.
>
yeah, i noticed that and that is why i used the sigkill_pending
initially. But after a deeper look
at the signal code, i found for SIGKILL ( signal we care about in this
patch ), tsk->pending is a
superset of tsk->signal->shared_pending.


--Ying
>
>
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