From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx147.postini.com [74.125.245.147]) by kanga.kvack.org (Postfix) with SMTP id 12B526B005A for ; Thu, 20 Dec 2012 17:27:04 -0500 (EST) Received: by mail-wi0-f172.google.com with SMTP id o1so4634107wic.5 for ; Thu, 20 Dec 2012 14:27:03 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <50D387FD.4020008@oracle.com> References: <50D387FD.4020008@oracle.com> From: Linus Torvalds Date: Thu, 20 Dec 2012 14:26:43 -0800 Message-ID: Subject: Re: [PATCH] ksm: make rmap walks more scalable Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Sasha Levin Cc: Hugh Dickins , Mel Gorman , Andrew Morton , Ingo Molnar , Petr Holasek , Linux Kernel Mailing List , linux-mm On Thu, Dec 20, 2012 at 1:49 PM, Sasha Levin wrote: > On 12/19/2012 08:44 PM, Hugh Dickins wrote: >> The rmap walks in ksm.c are like those in rmap.c: >> they can safely be done with anon_vma_lock_read(). >> >> Signed-off-by: Hugh Dickins >> --- > > Hi Hugh, > > This patch didn't fix the ksm oopses I'm seeing. > > This is with both patches applied: Looks like another NULL mm pointer in ksmd.. Hugh fixed one in 2832bc19f666 ("sched: numa: ksm: fix oops in task_numa_placment()"), this looks like more of the same. At a guess, it looks like get_mergeable_page() has a rmap_item with no mm. No idea how that happened. Hugh? Some race due to something that depended on the mmap_sem being exclusive, rather than for read-ownership? Linus -- 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