From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx127.postini.com [74.125.245.127]) by kanga.kvack.org (Postfix) with SMTP id C28086B0044 for ; Tue, 24 Apr 2012 13:17:42 -0400 (EDT) Received: by lbbgg6 with SMTP id gg6so948490lbb.14 for ; Tue, 24 Apr 2012 10:17:40 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4F96D6EE.6000809@redhat.com> References: <1335214564-17619-1-git-send-email-yinghan@google.com> <4F960257.9090509@kernel.org> <4F96D6EE.6000809@redhat.com> Date: Tue, 24 Apr 2012 10:17:40 -0700 Message-ID: Subject: Re: [RFC PATCH] do_try_to_free_pages() might enter infinite loop From: Ying Han Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Minchan Kim , KOSAKI Motohiro , Michal Hocko , Johannes Weiner , Mel Gorman , KAMEZAWA Hiroyuki , Minchan Kim , Hugh Dickins , Nick Piggin , Andrew Morton , linux-mm@kvack.org On Tue, Apr 24, 2012 at 9:38 AM, Rik van Riel wrote: > On 04/24/2012 12:36 PM, Ying Han wrote: > >> However, what if B frees a pages everytime before pages_scanned >> reaches the point, then we won't set zone->all_unreclaimable at all. >> If so, we reaches a livelock here... > > > If B keeps freeing pages, surely A will get a successful > allocation and there will not be a livelock? Ah, that is another piece of puzzle. We suspect the zone is under min_watermark due to previous alloc_flags (ALLOC_NO_WATERMARKS) and B returns the page under min which can not be allocated by A. Now we reset the zone->pages_scanned on freeing page regardless of the watermarks, so it is possible that zone is under min_watermark but !zone->all_unreclaimable. --Ying > > -- > All rights reversed -- 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