From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 12 Jun 2008 13:35:20 +0300 (EEST) From: Pekka J Enberg Subject: Re: repeatable slab corruption with LTP msgctl08 In-Reply-To: <20080611221324.42270ef2.akpm@linux-foundation.org> Message-ID: References: <20080611221324.42270ef2.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Nadia Derbey , Manfred Spraul , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Lameter List-ID: Hi Andrew, On Wed, 11 Jun 2008, Andrew Morton wrote: > version is ltp-full-20070228 (lots of retro-computing there). > > Config is at http://userweb.kernel.org/~akpm/config-vmm.txt > > ./testcases/bin/msgctl08 crashes after ten minutes or so: > > slab: Internal list corruption detected in cache 'size-128'(26), slabp f2905000(20). Hexdump: > > 000: 00 e0 12 f2 88 32 c0 f7 88 00 00 00 88 50 90 f2 > 010: 14 00 00 00 0f 00 00 00 00 00 00 00 ff ff ff ff > 020: fd ff ff ff fd ff ff ff fd ff ff ff fd ff ff ff > 030: fd ff ff ff fd ff ff ff fd ff ff ff fd ff ff ff > 040: fd ff ff ff fd ff ff ff 00 00 00 00 fd ff ff ff > 050: fd ff ff ff fd ff ff ff 19 00 00 00 17 00 00 00 > 060: fd ff ff ff fd ff ff ff 0b 00 00 00 fd ff ff ff > 070: fd ff ff ff fd ff ff ff fd ff ff ff fd ff ff ff > 080: 10 00 00 00 Looking at the above dump, slabp->free is 0x0f and the bufctl it points to is 0xff ("BUFCTL_END") which marks the last element in the chain. This is wrong as the total number of objects in the slab (cachep->num) is 26 but the number of objects in use (slabp->inuse) is 20. So somehow you have managed to lost 6 objects from the bufctl chain. I really don't understand how your bufctl chains has so many BUFCTL_END elements in the first place. It's doesn't look like the memory has been stomped on (slab->s_mem, for example, is 0xf2906088), so I'd look for a double kfree() of size 128 somewhere... Pekka -- 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