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Date: Tue, 11 Jun 2013 12:19:52 -0400
From: Sasha Levin <sasha.levin@oracle.com>
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To: Eric Dumazet <eric.dumazet@gmail.com>
CC: Christoph Lameter <cl@gentwo.org>, Pekka Enberg <penberg@kernel.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] slab: prevent warnings when allocating with __GFP_NOWARN
References: <1370891880-2644-1-git-send-email-sasha.levin@oracle.com>  <CAOJsxLGDH2iwznRkP-iwiMZw7Ee3mirhjLvhShrWLHR0qguRxA@mail.gmail.com>  <51B62F6B.8040308@oracle.com>  <0000013f3075f90d-735942a8-b4b8-413f-a09e-57d1de0c4974-000000@email.amazonses.com>  <51B67553.6020205@oracle.com>  <CAOJsxLH56xqCoDikYYaY_guqCX=S4rcVfDJQ4ki=r-PkNQW9ug@mail.gmail.com>  <51B72323.8040207@oracle.com>  <0000013f33cdc631-eadb07d1-ef08-4e2c-a218-1997eb86cde9-000000@email.amazonses.com>  <51B73F38.6040802@kernel.org>  <0000013f33d58923-88767793-2187-476d-b500-dba3c22607aa-000000@email.amazonses.com>  <51B745F9.9080609@oracle.com> <1370967193.3252.47.camel@edumazet-glaptop>
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On 06/11/2013 12:13 PM, Eric Dumazet wrote:
> On Tue, 2013-06-11 at 11:44 -0400, Sasha Levin wrote:
>> On 06/11/2013 11:23 AM, Christoph Lameter wrote:
>>> On Tue, 11 Jun 2013, Pekka Enberg wrote:
>>>
>>>> So you're OK with going forward with Sasha's patch? It's needed
>>>> because __GFP_NOWARN was specifically added there to fix this
>>>> issue earlier.
>>>
>>> Why dont we fix the call site to use vmalloc instead for larger allocs?
>>>
>>
>> We should probably be doing both.
>
> Allowing a pipe to store thousands of page refs seems quite useless and
> dangerous.

It might be, but you need CAP_SYS_RESOURCE to go into the dangerous
zone (>pipe_max_size).

So if root (or someone with that cap) wants to go there, as Rusty says:
"Root asked, we do."


Thanks,
Sasha