From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx140.postini.com [74.125.245.140]) by kanga.kvack.org (Postfix) with SMTP id 6E0C56B0068 for ; Thu, 3 Jan 2013 07:24:21 -0500 (EST) Date: Thu, 3 Jan 2013 13:24:17 +0100 From: Petr Holasek Subject: Re: [PATCH v7 1/2] KSM: numa awareness sysfs knob Message-ID: <20130103122416.GB2277@thinkpad-work.redhat.com> References: <20121224050817.GA25749@kroah.com> <1356658337-12540-1-git-send-email-pholasek@redhat.com> <1357015310.1379.2.camel@kernel.cn.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1357015310.1379.2.camel@kernel.cn.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Simon Jeons Cc: Hugh Dickins , Andrea Arcangeli , Andrew Morton , Izik Eidus , Rik van Riel , David Rientjes , Sasha Levin , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Anton Arapov Hi Simon, On Mon, 31 Dec 2012, Simon Jeons wrote: > On Fri, 2012-12-28 at 02:32 +0100, Petr Holasek wrote: > > > > v7: - added sysfs ABI documentation for KSM > > Hi Petr, > > How you handle "memory corruption because the ksm page still points to > the stable_node that has been freed" mentioned by Andrea this time? > > > > > + /* > > + * If tree_page has been migrated to another NUMA node, it > > + * will be flushed out and put into the right unstable tree > > + * next time: only merge with it if merge_across_nodes. > > Why? Do you mean swap based migration? Or where I miss ....? > It can be physical page migration triggered by page compaction, memory hotplug or some NUMA sched/memory balancing algorithm developed recently. > > + * Just notice, we don't have similar problem for PageKsm > > + * because their migration is disabled now. (62b61f611e) > > + */ Migration of KSM pages is disabled now, you can look into ^^^ commit and changes introduced to migrate.c. > > + if (!ksm_merge_across_nodes && page_to_nid(tree_page) != nid) { > > + put_page(tree_page); > > + return NULL; > > + } > > + > > ret = memcmp_pages(page, tree_page); -- 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