From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 216F86B004D for ; Fri, 27 Nov 2009 07:45:30 -0500 (EST) Date: Fri, 27 Nov 2009 12:45:04 +0000 (GMT) From: Hugh Dickins Subject: Re: [PATCH 1/9] ksm: fix mlockfreed to munlocked In-Reply-To: <20091126162011.GG13095@csn.ul.ie> Message-ID: References: <20091126162011.GG13095@csn.ul.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Mel Gorman , Rik van Riel Cc: Andrew Morton , Izik Eidus , Andrea Arcangeli , Chris Wright , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Thu, 26 Nov 2009, Mel Gorman wrote: > On Tue, Nov 24, 2009 at 04:40:55PM +0000, Hugh Dickins wrote: > > When KSM merges an mlocked page, it has been forgetting to munlock it: > > that's been left to free_page_mlock(), which reports it in /proc/vmstat > > as unevictable_pgs_mlockfreed instead of unevictable_pgs_munlocked (and > > whinges "Page flag mlocked set for process" in mmotm, whereas mainline > > is silently forgiving). Call munlock_vma_page() to fix that. > > > > Signed-off-by: Hugh Dickins > > Acked-by: Mel Gorman Rik & Mel, thanks for the Acks. But please clarify: that patch was for mmotm and hopefully 2.6.33, but the vmstat issue (minus warning message) is there in 2.6.32-rc. Should I (a) forget it for 2.6.32 (b) rush Linus a patch for 2.6.32 final (c) send a patch for 2.6.32.stable later on ? I just don't have a feel for how important this is. Typically, these pages are immediately freed, and the only issue is which stats they get added to; but if fork has copied them into other mms, then such pages might stay unevictable indefinitely, despite no longer being in any mlocked vma. There's a remark in munlock_vma_page(), apropos a different issue, /* * We lost the race. let try_to_unmap() deal * with it. At least we get the page state and * mlock stats right. However, page is still on * the noreclaim list. We'll fix that up when * the page is eventually freed or we scan the * noreclaim list. */ which implies that sometimes we scan the unevictable list and resolve such cases. But I wonder if that's nowadays the case? > > > --- > > Is this a fix that I ought to backport to 2.6.32? It does rely on part of > > an earlier patch (moved unlock_page down), so does not apply cleanly as is. Thanks, Hugh -- 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