From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 1A9926B0011 for ; Tue, 31 May 2011 10:14:32 -0400 (EDT) Date: Tue, 31 May 2011 16:14:02 +0200 From: Andrea Arcangeli Subject: Re: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous Message-ID: <20110531141402.GK19505@random.random> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110531133340.GB3490@barrios-laptop> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim 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 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. 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. -- 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