From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752677AbcGAUFa (ORCPT ); Fri, 1 Jul 2016 16:05:30 -0400 Received: from outbound-smtp09.blacknight.com ([46.22.139.14]:33141 "EHLO outbound-smtp09.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752610AbcGAUF1 (ORCPT ); Fri, 1 Jul 2016 16:05:27 -0400 From: Mel Gorman To: Andrew Morton , Linux-MM Cc: Rik van Riel , Vlastimil Babka , Johannes Weiner , LKML , Mel Gorman Subject: [PATCH 21/31] mm, page_alloc: Wake kswapd based on the highest eligible zone Date: Fri, 1 Jul 2016 21:01:29 +0100 Message-Id: <1467403299-25786-22-git-send-email-mgorman@techsingularity.net> X-Mailer: git-send-email 2.6.4 In-Reply-To: <1467403299-25786-1-git-send-email-mgorman@techsingularity.net> References: <1467403299-25786-1-git-send-email-mgorman@techsingularity.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The ac_classzone_idx is used as the basis for waking kswapd and that is based on the preferred zoneref. If the preferred zoneref's highest zone is lower than what is available on other nodes, it's possible that kswapd is woken on a zone with only higher, but still eligible, zones. As classzone_idx is strictly adhered to now, it causes a problem because eligible pages are skipped. For example, node 0 has only DMA32 and node 1 has only NORMAL. An allocating context running on node 0 may wake kswapd on node 1 telling it to skip all NORMAL pages. Signed-off-by: Mel Gorman --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2fe2fbb4f2ad..b10bee2e5968 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3415,7 +3415,7 @@ static void wake_all_kswapds(unsigned int order, const struct alloc_context *ac) for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx, ac->nodemask) { if (last_pgdat != zone->zone_pgdat) - wakeup_kswapd(zone, order, ac_classzone_idx(ac)); + wakeup_kswapd(zone, order, ac->high_zoneidx); last_pgdat = zone->zone_pgdat; } } -- 2.6.4