Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752179AbdDKQlm (ORCPT ); Tue, 11 Apr 2017 12:41:42 -0400 Received: from mx2.suse.de ([195.135.220.15]:35673 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750721AbdDKQlk (ORCPT ); Tue, 11 Apr 2017 12:41:40 -0400 Date: Tue, 11 Apr 2017 18:41:36 +0200 From: Michal Hocko To: Christoph Lameter Cc: Kees Cook , Andrew Morton , Pekka Enberg , David Rientjes , Joonsoo Kim , Linux-MM , LKML Subject: Re: [PATCH] mm: Add additional consistency check Message-ID: <20170411164134.GA21171@dhcp22.suse.cz> References: <20170404151600.GN15132@dhcp22.suse.cz> <20170404194220.GT15132@dhcp22.suse.cz> <20170404201334.GV15132@dhcp22.suse.cz> <20170411134618.GN6729@dhcp22.suse.cz> <20170411141956.GP6729@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 936 Lines: 30 On Tue 11-04-17 11:16:42, Cristopher Lameter wrote: > On Tue, 11 Apr 2017, Michal Hocko wrote: > > > static inline void *index_to_obj(struct kmem_cache *cache, struct page *page, > > @@ -3813,14 +3818,18 @@ void kfree(const void *objp) > > { > > struct kmem_cache *c; > > unsigned long flags; > > + struct page *page; > > > > trace_kfree(_RET_IP_, objp); > > > > if (unlikely(ZERO_OR_NULL_PTR(objp))) > > return; > > + page = virt_to_head_page(obj); > > + if (CHECK_DATA_CORRUPTION(!PageSlab(page))) > > There is a flag SLAB_DEBUG_OBJECTS that is available for this check. Which is way too late, at least for the kfree path. page->slab_cache on anything else than PageSlab is just a garbage. And my understanding of the patch objective is to stop those from happening. > Consistency checks are configuraable in the slab allocator. and they have to be compiled in (at least for SLAB) AFAIR. -- Michal Hocko SUSE Labs