From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vn0-f53.google.com (mail-vn0-f53.google.com [209.85.216.53]) by kanga.kvack.org (Postfix) with ESMTP id 58DBF6B0032 for ; Thu, 11 Jun 2015 13:26:14 -0400 (EDT) Received: by vnbg190 with SMTP id g190so1981003vnb.8 for ; Thu, 11 Jun 2015 10:26:14 -0700 (PDT) Received: from resqmta-ch2-12v.sys.comcast.net (resqmta-ch2-12v.sys.comcast.net. [2001:558:fe21:29:69:252:207:44]) by mx.google.com with ESMTPS id ui18si2040724vdb.37.2015.06.11.10.26.12 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Thu, 11 Jun 2015 10:26:13 -0700 (PDT) Date: Thu, 11 Jun 2015 12:26:11 -0500 (CDT) From: Christoph Lameter Subject: Re: [RFC][PATCH 0/5] do not dereference NULL pools in pools' destroy() functions In-Reply-To: <20150609191755.867a36c3.akpm@linux-foundation.org> Message-ID: References: <1433851493-23685-1-git-send-email-sergey.senozhatsky@gmail.com> <20150609142523.b717dba6033ee08de997c8be@linux-foundation.org> <20150609185150.8c9fed8d.akpm@linux-foundation.org> <20150609191755.867a36c3.akpm@linux-foundation.org> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: 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 On Tue, 9 Jun 2015, Andrew Morton wrote: > > > More than half of the kmem_cache_destroy() callsites are declining that > > > value by open-coding the NULL test. That's reality and we should recognize > > > it. > > > > Well that may just indicate that we need to have a look at those > > callsites and the reason there to use a special cache at all. > > This makes no sense. Go look at the code. > drivers/staging/lustre/lustre/llite/super25.c, for example. It's all > in the basic unwind/recover/exit code. That is screwed up code. I'd do that without the checks simply with a series of kmem_cache_destroys(). > > If the cache > > is just something that kmalloc can provide then why create a special > > cache. On the other hand if something special needs to be accomplished > > then it would make sense to have special processing on kmem_cache_destroy. > > This has nothing to do with anything. We're talking about a basic "if > I created this cache then destroy it" operation. As you see in this code snipped you cannot continue if a certain operation during setup fails. At that point it is known which caches exist and therefore kmem_cache_destroy() can be called without the checks. > It's a common pattern. mm/ exists to serve client code and as a lot of > client code is doing this, we should move it into mm/ so as to serve > client code better. Doing this seems to encourage sloppy coding practices. -- 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