From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f43.google.com (mail-pa0-f43.google.com [209.85.220.43]) by kanga.kvack.org (Postfix) with ESMTP id 7A0BD6B003A for ; Wed, 2 Oct 2013 11:54:52 -0400 (EDT) Received: by mail-pa0-f43.google.com with SMTP id hz1so1213160pad.2 for ; Wed, 02 Oct 2013 08:54:52 -0700 (PDT) Date: Wed, 2 Oct 2013 16:54:18 +0100 From: Catalin Marinas Subject: Re: [PATCH] slub: Proper kmemleak tracking if CONFIG_SLUB_DEBUG disabled Message-ID: <20131002155417.GB29794@arm.com> References: <5245ECC3.8070200@gmail.com> <00000141799dd4b3-f6df96c0-1003-427d-9bd8-f6455622f4ea-000000@email.amazonses.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: "Bird, Tim" Cc: Christoph Lameter , Frank Rowand , Pekka Enberg , Matt Mackall , "linux-mm@kvack.org" , Linux Kernel list , "Bobniev, Roman" , =?iso-8859-1?Q?Andersson=2C_Bj=F6rn?= On Wed, Oct 02, 2013 at 04:33:47PM +0100, Bird, Tim wrote: > On Wednesday, October 02, 2013 7:41 AM, Christoph Lameter [cl@linux.com] wrote: > > > >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 internally > before sending this one, did exactly that. I guess Roman gets to say "I told > 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=n but CONFIG_DEBUG_KMEMLEAK=y, > 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 keep > all the checks in the hooks? > > Personally, I like the idea of keeping bookeeping/tracing/debug stuff in hook > routines. I also like de-coupling CONFIG_SLUB_DEBUG and CONFIG_DEBUG_KMEMLEAK, > 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 the > kmemleak stuff out from under CONFIG_SLUB_DEBUG. > We'll have to see if the ifdefs get a little messy. Kmemleak doesn't depend on SLUB_DEBUG (at least it didn't originally ;), so I don't think we should add an artificial dependency (or select). Can we have kmemleak_*() calls in both debug and !debug hooks? -- Catalin -- 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