linux-kernel - Re: [PATCH] slab: prevent warnings when allocating with __GFP

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Message-ID: <51B77433.4080305@oracle.com>
Date:	Tue, 11 Jun 2013 15:02:11 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Christoph Lameter <cl@...two.org>,
	Pekka Enberg <penberg@...nel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] slab: prevent warnings when allocating with __GFP_NOWARN

On 06/11/2013 12:37 PM, Eric Dumazet wrote:
> On Tue, 2013-06-11 at 12:19 -0400, Sasha Levin wrote:
>
>> 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."
>
> Yes and no : adding a test to select vmalloc()/vfree() instead of
> kmalloc()/kfree() will slow down regular users asking 32 pages in their
> pipe.
>
> If there is no _sensible_ use for large pipes even for root, please do
> not bloat the code just because we can.

The code to allow root to grow pipes is quite ancient.

Either we drop it or we fix it, leaving it broken as it is is silly.


Thanks,
Sasha

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