From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933858AbaEFDZy (ORCPT ); Mon, 5 May 2014 23:25:54 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:36032 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933740AbaEFDZw (ORCPT ); Mon, 5 May 2014 23:25:52 -0400 Date: Mon, 05 May 2014 23:25:50 -0400 (EDT) Message-Id: <20140505.232550.1139149215179650645.davem@davemloft.net> To: sam@ravnborg.org Cc: linux-kernel@vger.kernel.org, iamjoonsoo.kim@lge.com, sparclinux@vger.kernel.org, hannes@cmpxchg.org, cl@linux.com, penberg@kernel.org, torvalds@linux-foundation.org Subject: Re: [PATCH] slab: Fix off by one in object max number tests. From: David Miller In-Reply-To: <20140505.170855.814445464231092040.davem@davemloft.net> References: <20140505.165756.1229178386133288960.davem@davemloft.net> <20140505210507.GA5130@ravnborg.org> <20140505.170855.814445464231092040.davem@davemloft.net> X-Mailer: Mew version 6.5 on Emacs 24.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.7 (shards.monkeyblade.net [149.20.54.216]); Mon, 05 May 2014 20:25:52 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Miller Date: Mon, 05 May 2014 17:08:55 -0400 (EDT) > From: Sam Ravnborg > Date: Mon, 5 May 2014 23:05:07 +0200 > >> On Mon, May 05, 2014 at 04:57:56PM -0400, David Miller wrote: >>> From: David Miller >>> Date: Mon, 05 May 2014 16:20:04 -0400 (EDT) >>> >>> > >>> > If freelist_idx_t is a byte, SLAB_OBJ_MAX_NUM should be 255 not 256, >>> > and likewise if freelist_idx_t is a short, then it should be 65535 not >>> > 65536. >>> > >>> > Fixes: a41adfa ("slab: introduce byte sized index for the freelist of a slab") >>> > Signed-off-by: David S. Miller >>> > --- >>> > >>> > This was leading to all kinds of random crashes on sparc64 where PAGE_SIZE >>> > is 8192. One problem shown was that if spinlock debugging was enabled, >>> > we'd get deadlocks in copy_pte_range() or do_wp_page() with the same cpu >>> > already holding a lock it shouldn't hold, or the lock belonging to a >>> > completely unrelated process. >>> >>> It turns out that after some more testing, I'm still getting spinlock >>> debugging problems with this fix applied. >>> >>> The change is still very much correct I think, however. >> >> There is a related patch in this area which I think is not yet applied. >> >> See: https://lkml.org/lkml/2014/4/18/28 >> >> Maybe this is realted. > > Thanks, I'm testing with that patch added as well. I can confirm that this fixes my problems completely.