From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id CA0C76B0070 for ; Wed, 2 Oct 2013 11:33:52 -0400 (EDT) Received: by mail-pa0-f47.google.com with SMTP id kp14so1176889pab.6 for ; Wed, 02 Oct 2013 08:33:52 -0700 (PDT) From: "Bird, Tim" Date: Wed, 2 Oct 2013 17:33:47 +0200 Subject: RE: [PATCH] slub: Proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled Message-ID: References: <5245ECC3.8070200@gmail.com>,<00000141799dd4b3-f6df96c0-1003-427d-9bd8-f6455622f4ea-000000@email.amazonses.com> In-Reply-To: <00000141799dd4b3-f6df96c0-1003-427d-9bd8-f6455622f4ea-000000@email.amazonses.com> Content-Language: en-US Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter , Frank Rowand Cc: Pekka Enberg , Matt Mackall , "linux-mm@kvack.org" , Linux Kernel list , Catalin Marinas , "Bobniev, Roman" , =?iso-8859-1?Q?=22Andersson=2C_Bj=F6rn=22?= On Wednesday, October 02, 2013 7:41 AM, Christoph Lameter [cl@linux.com] wr= ote: > >On Fri, 27 Sep 2013, Frank Rowand wrote: > >> Move the kmemleak code for small block allocation out from >> under CONFIG_SLUB_DEBUG. > >Well in that case it may be better to move the hooks as a whole out of >the CONFIG_SLUB_DEBUG section. Do the #ifdeffering for each call from the >hooks instead. > >The point of the hook functions is to separate the hooks out of the >functions so taht they do not accumulate in the main code. > >The patch moves one hook back into the main code. Please keep the checks >in the hooks. Thanks for the feedback. Roman's first patch, which we discussed internall= y before sending this one, did exactly that. I guess Roman gets to say "I to= ld you so." :-) My bad for telling him to change it. We'll refactor along the lines that you describe, and send another one. The problem child is actually the unconditional call to kmemleak_alloc() in kmalloc_large_node() (in slub.c). The problem comes because that call is unconditional on CONFIG_SLUB_DEBUG but the kmemleak calls in the hook routines are conditional on CONFIG_SLUB_DEBUG. So if you have CONFIG_SLUB_DEBUG=3Dn but CONFIG_DEBUG_KMEMLEAK=3Dy, you get the false reports. Now, there are kmemleak calls in kmalloc_large_node() and kfree() that don'= t follow the "hook" pattern. Should these be moved to 'hook' routines, to ke= ep all the checks in the hooks? Personally, I like the idea of keeping bookeeping/tracing/debug stuff in ho= ok routines. I also like de-coupling CONFIG_SLUB_DEBUG and CONFIG_DEBUG_KMEML= EAK, but maybe others have a different opinon. Unless someone speaks up, we'll move the the currently in-function kmemleak calls into hooks, and all of th= e kmemleak stuff out from under CONFIG_SLUB_DEBUG. We'll have to see if the ifdefs get a little messy. -- Tim -- 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