Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933332AbbFJBLo (ORCPT ); Tue, 9 Jun 2015 21:11:44 -0400 Received: from resqmta-ch2-11v.sys.comcast.net ([69.252.207.43]:45697 "EHLO resqmta-ch2-11v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933247AbbFJBL1 (ORCPT ); Tue, 9 Jun 2015 21:11:27 -0400 Date: Tue, 9 Jun 2015 20:11:25 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@east.gentwo.org To: Andrew Morton cc: Sergey Senozhatsky , Minchan Kim , Pekka Enberg , Joonsoo Kim , Michal Hocko , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, sergey.senozhatsky.work@gmail.com, Joe Perches Subject: Re: [RFC][PATCH 0/5] do not dereference NULL pools in pools' destroy() functions In-Reply-To: <20150609142523.b717dba6033ee08de997c8be@linux-foundation.org> Message-ID: References: <1433851493-23685-1-git-send-email-sergey.senozhatsky@gmail.com> <20150609142523.b717dba6033ee08de997c8be@linux-foundation.org> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1031 Lines: 24 On Tue, 9 Jun 2015, Andrew Morton wrote: > Well I like it, even though it's going to cause a zillion little cleanup > patches. > > checkpatch already has a "kfree(NULL) is safe and this check is > probably not required" test so I guess Joe will need to get busy ;) > > I'll park these patches until after 4.1 is released - it's getting to > that time... Why do this at all? I understand that kfree/kmem_cache_free can take a null pointer but this is the destruction of a cache and it usually requires multiple actions to clean things up and these actions have to be properly sequenced. All other processors have to stop referencing this cache before it can be destroyed. I think failing if someone does something strange like doing cache destruction with a NULL pointer is valuable. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/