From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id F18566B0023 for ; Tue, 31 May 2011 10:38:39 -0400 (EDT) Received: by pwi12 with SMTP id 12so2593887pwi.14 for ; Tue, 31 May 2011 07:38:38 -0700 (PDT) Date: Tue, 31 May 2011 23:38:30 +0900 From: Minchan Kim Subject: Re: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous Message-ID: <20110531143830.GC13418@barrios-laptop> References: <20110530131300.GQ5044@csn.ul.ie> <20110530143109.GH19505@random.random> <20110530153748.GS5044@csn.ul.ie> <20110530165546.GC5118@suse.de> <20110530175334.GI19505@random.random> <20110531121620.GA3490@barrios-laptop> <20110531122437.GJ19505@random.random> <20110531133340.GB3490@barrios-laptop> <20110531141402.GK19505@random.random> <20110531143734.GB13418@barrios-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110531143734.GB13418@barrios-laptop> Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: Mel Gorman , Mel Gorman , akpm@linux-foundation.org, Ury Stankevich , KOSAKI Motohiro , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@kernel.org On Tue, May 31, 2011 at 11:37:35PM +0900, Minchan Kim wrote: > On Tue, May 31, 2011 at 04:14:02PM +0200, Andrea Arcangeli wrote: > > On Tue, May 31, 2011 at 10:33:40PM +0900, Minchan Kim wrote: > > > I checked them before sending patch but I got failed to find strange things. :( > > > > My review also doesn't show other bugs in migrate_pages callers like > > that one. > > > > > Now I am checking the page's SwapBacked flag can be changed > > > between before and after of migrate_pages so accounting of NR_ISOLATED_XX can > > > make mistake. I am approaching the failure, too. Hmm. > > > > When I checked that, I noticed the ClearPageSwapBacked in swapcache if > > radix insertion fails, but that happens before adding the page in the > > LRU so it shouldn't have a chance to be isolated. > > True. > > > > > So far I only noticed an unsafe page_count in > > vmscan.c:isolate_lru_pages but that should at worst result in a > > invalid pointer dereference as random result from that page_count is > > not going to hurt and I think it's only a theoretical issue. > > > Yes. You find a new BUG. > It seems to be related to this problem but it should be solved although typo : It doesn't seem to be. - Kind regards Minchan Kim -- 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