From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx175.postini.com [74.125.245.175]) by kanga.kvack.org (Postfix) with SMTP id 55F766B0031 for ; Mon, 10 Jun 2013 20:55:04 -0400 (EDT) Message-ID: <51B67553.6020205@oracle.com> Date: Mon, 10 Jun 2013 20:54:43 -0400 From: Sasha Levin MIME-Version: 1.0 Subject: Re: [PATCH] slab: prevent warnings when allocating with __GFP_NOWARN References: <1370891880-2644-1-git-send-email-sasha.levin@oracle.com> <51B62F6B.8040308@oracle.com> <0000013f3075f90d-735942a8-b4b8-413f-a09e-57d1de0c4974-000000@email.amazonses.com> In-Reply-To: <0000013f3075f90d-735942a8-b4b8-413f-a09e-57d1de0c4974-000000@email.amazonses.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: Pekka Enberg , "linux-mm@kvack.org" , Andrew Morton , LKML On 06/10/2013 07:40 PM, Christoph Lameter wrote: > On Mon, 10 Jun 2013, Sasha Levin wrote: > >> [ 1691.807621] Call Trace: >> [ 1691.809473] [] dump_stack+0x4e/0x82 >> [ 1691.812783] [] warn_slowpath_common+0x82/0xb0 >> [ 1691.817011] [] warn_slowpath_null+0x15/0x20 >> [ 1691.819936] [] kmalloc_slab+0x2f/0xb0 >> [ 1691.824942] [] __kmalloc+0x24/0x4b0 >> [ 1691.827285] [] ? security_capable+0x13/0x20 >> [ 1691.829405] [] ? pipe_fcntl+0x107/0x210 >> [ 1691.831827] [] pipe_fcntl+0x107/0x210 >> [ 1691.833651] [] ? fget_raw_light+0x130/0x3f0 >> [ 1691.835343] [] SyS_fcntl+0x60b/0x6a0 >> [ 1691.837008] [] tracesys+0xe1/0xe6 >> >> The caller specifically sets __GFP_NOWARN presumably to avoid this warning on >> slub but I'm not sure if there's any other reason. > > There must be another reason. Lets fix this. My, I feel silly now. I was the one who added __GFP_NOFAIL in the first place in 2ccd4f4d ("pipe: fail cleanly when root tries F_SETPIPE_SZ with big size"). What happens is that root can go ahead and specify any size it wants to be used as buffer size - and the kernel will attempt to comply by allocation that buffer. Which fails if the size is too big. Either way, even if we do end up doing something different, shouldn't we prevent slab from spewing a warning if __GFP_NOWARN is passed? Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org