Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932647Ab2ENWe7 (ORCPT ); Mon, 14 May 2012 18:34:59 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:54597 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932312Ab2ENWe5 (ORCPT ); Mon, 14 May 2012 18:34:57 -0400 Subject: Re: [PATCH v2] mm: Fix slab->page _count corruption. From: Eric Dumazet To: Pravin B Shelar Cc: cl@linux.com, penberg@kernel.org, mpm@selenic.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, jesse@nicira.com, abhide@nicira.com In-Reply-To: <1337034597-1826-1-git-send-email-pshelar@nicira.com> References: <1337034597-1826-1-git-send-email-pshelar@nicira.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 15 May 2012 00:34:52 +0200 Message-ID: <1337034892.8512.652.camel@edumazet-glaptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 921 Lines: 23 On Mon, 2012-05-14 at 15:29 -0700, 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. I say again : Page is owned by slub, so get_page() or put_page() is not allowed ? How is put_page() going to work with order-1 or order-2 allocations ? Me very confused by these Nicira patches. -- 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/