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Subject: Re: [PATCH] staging: android: ion: Bail out upon SIGKILL when
 allocating memory.
To:     Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Sumit Semwal <sumit.semwal@linaro.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>
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 <b863d9a0-ac5b-8187-4373-b0532cf60e76@i-love.sakura.ne.jp>
From:   Laura Abbott <labbott@redhat.com>
Message-ID: <37ac2d6d-3fc6-53eb-c2cd-20c0e9ac2054@redhat.com>
Date:   Mon, 1 Jul 2019 17:21:39 -0400
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On 7/1/19 5:02 PM, Tetsuo Handa wrote:
> On 2019/07/01 23:02, Sumit Semwal wrote:
>>> Acked-by: Laura Abbott <labbott@redhat.com>
>> fwiw, Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
> 
> Thank you for responding. You can carry this patch via whichever tree you like.
> 
> By the way, is "memory allocation from ion_system_heap_allocate() is calling
> ion_system_heap_shrink()"
> ( https://lkml.kernel.org/r/03763360-a7de-de87-eb90-ba7838143930@I-love.SAKURA.ne.jp )
> what we want? Such memory allocations might not want to call shrinkers...
> 

For what Ion gets typically used for we do want to be calling shrinkers.
I've had discussions with people in the past about the risk of Ion as
DoS vector due to its ability to allocate large amounts of memory.
At the very least, we probably shouldn't be trying to call the Ion shrinker
when we're in the middle of an ion allocation since shrinking won't do us
any good. We're in the process of re-working Ion at the moment so this
might be a good topic to bring up again.

Thanks,
Laura