From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Vegard Nossum" Subject: Re: linux-next: Tree for July 18: warning at kernel/lockdep.c:2068 trace_hardirqs_on_caller Date: Sun, 20 Jul 2008 00:27:26 +0200 Message-ID: <19f34abd0807191527u61c5ed61kffe2279c8d46915d@mail.gmail.com> References: <20080718195352.e562a00f.sfr@canb.auug.org.au> <200807190928.33978.m.kozlowski@tuxland.pl> <19f34abd0807190255x304173d4wf2bfabb2d5bce511@mail.gmail.com> <19f34abd0807190559y2fe5ebf9h7095793e82de3122@mail.gmail.com> <20080719221723.GB5578@suse.de> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type :content-transfer-encoding:content-disposition:references; bh=2GiwvPJjyKeGiIPWJi8DANYZe6xcK73WQdKCTcvCSsE=; b=mF7hGqnwPHaUd5T5mLDjA3hDuelslv7vvGR5l2BadvOe73si4btBUnegf1HD+vonpH aZAufTJyClFxxUBnVLxAYRmrN+MBaX8RVXjYaZgXIgD32YBsvgJTyhkCGi9R5+eAJKOK aom1xaSNmqyh26VxVuUdsaF7C6wDbqcGXUwfQ= In-Reply-To: <20080719221723.GB5578@suse.de> Content-Disposition: inline Sender: linux-next-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Greg KH Cc: Mariusz Kozlowski , Dave Hansen , Stephen Rothwell , kernel-testers@vger.kernel.org, linux-next@vger.kernel.org, LKML , Pekka Enberg On Sun, Jul 20, 2008 at 12:17 AM, Greg KH wrote: > On Sat, Jul 19, 2008 at 02:59:12PM +0200, Vegard Nossum wrote: >> On Sat, Jul 19, 2008 at 11:55 AM, Vegard Nossum wrote: >> > What I don't get here is how SLUB can be used this early in the boot >> > process. Notice that this is still miles away from the >> > >> > SLUB: Genslabs=12, HWalign=128, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 >> > >> > line, which comes much later. And that kobject_init() _is_ calling >> > kzalloc() via verify_dynamic_kobject_allocation(). Isn't this an >> > error? >> > >> > (Unfortunately, my "git log" doesn't turn up any recent changes for >> > any of the affected code paths here.) >> >> Ehe... and this is the reason why: The code was added by this patch: >> >> commit 0e3638d1e04040121af00195f7e4628078246489 >> Author: Dave Hansen >> Date: Thu Mar 16 17:30:16 2006 -0800 >> >> warn when statically-allocated kobjects are used >> >> ..which only exists in -next. Is that just a truly ancient patch, or >> did somebody forget to adjust their clock? > > It is truely a very old patch, that only lives in my tree, and currently > isn't planned to go to Linus any year soon. > > But it has a very long history of living in the -mm tree, and finding > real bugs, it's just not "safe" enough to go to Linus's tree. Unless > you think it is? Hm. In this case, the patch is not even reporting a problem, it is in fact in error itself. The problem is that it calls kzalloc() before the slab caches have been set up. (Yes, it's a wonder that nothing crashed.) I can only suggest the addendum if (!slab_is_available()) return; Vegard -- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036