From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx137.postini.com [74.125.245.137]) by kanga.kvack.org (Postfix) with SMTP id 6C44D6B004D for ; Mon, 14 May 2012 14:59:02 -0400 (EDT) Date: Mon, 14 May 2012 13:58:59 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH 2/2] mm: Fix slab->page _count corruption. In-Reply-To: <1337020900-20120-1-git-send-email-pshelar@nicira.com> Message-ID: References: <1337020900-20120-1-git-send-email-pshelar@nicira.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Pravin B Shelar Cc: penberg@kernel.org, mpm@selenic.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jesse@nicira.com, abhide@nicira.com On Mon, 14 May 2012, Pravin B Shelar wrote: > On arches that do not support this_cpu_cmpxchg_double slab_lock is used > to do atomic cmpxchg() on double word which contains page->_count. > page count can be changed from get_page() or put_page() without taking > slab_lock. That corrupts page counter. > > Following patch fixes it by moving page->_count out of cmpxchg_double > data. So that slub does no change it while updating slub meta-data in > struct page. Ugly. Maybe its best to not touch the count in the page lock case in slub? You could accomplish that by changing the definition of counters in mm_types.h. Make it unsigned instead of unsigned long so that it only covers the first part of the struct (which excludes the refcounter) -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org