From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756775AbbAZU2o (ORCPT ); Mon, 26 Jan 2015 15:28:44 -0500 Received: from resqmta-po-03v.sys.comcast.net ([96.114.154.162]:38481 "EHLO resqmta-po-03v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756706AbbAZU2f (ORCPT ); Mon, 26 Jan 2015 15:28:35 -0500 Date: Mon, 26 Jan 2015 14:28:33 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Vladimir Davydov cc: Andrew Morton , Pekka Enberg , David Rientjes , Joonsoo Kim , Johannes Weiner , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm 2/3] slab: zap kmem_cache_shrink return value In-Reply-To: <20150126201602.GA3317@esperanza> Message-ID: References: <20150126170418.GC28978@esperanza> <20150126194838.GB2660@esperanza> <20150126201602.GA3317@esperanza> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 26 Jan 2015, Vladimir Davydov wrote: > Right, but I just don't see why a subsystem using a kmem_cache would > need to check whether there are any objects left in the cache. I mean, > it should somehow keep track of the objects it's allocated anyway, e.g. > by linking them in a list. That means it must already have a way to > check if it is safe to destroy its cache or not. The acpi subsystem did that at some point. > Suppose we leave the return value as is. A subsystem, right before going > to destroy a cache, calls kmem_cache_shrink, which returns 1 (slab is > not empty). What is it supposed to do then? That is up to the subsystem. If it has a means of tracking down the missing object then it can deal with it. If not then it cannot shutdown the cache and do a proper recovery action.