From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754525AbbJSSNk (ORCPT ); Mon, 19 Oct 2015 14:13:40 -0400 Received: from gum.cmpxchg.org ([85.214.110.215]:49027 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754048AbbJSSNj (ORCPT ); Mon, 19 Oct 2015 14:13:39 -0400 From: Johannes Weiner To: Andrew Morton Cc: Vladimir Davydov , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm: vmscan: count slab shrinking results after each shrink_slab() Date: Mon, 19 Oct 2015 14:13:35 -0400 Message-Id: <1445278415-21138-1-git-send-email-hannes@cmpxchg.org> X-Mailer: git-send-email 2.6.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org cb731d6 ("vmscan: per memory cgroup slab shrinkers") sought to optimize accumulating slab reclaim results in sc->nr_reclaimed only once per zone, but the memcg hierarchy walk itself uses sc->nr_reclaimed as an exit condition. This can lead to overreclaim. Signed-off-by: Johannes Weiner --- mm/vmscan.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 27d580b..a02654e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2441,11 +2441,18 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc, shrink_lruvec(lruvec, swappiness, sc, &lru_pages); zone_lru_pages += lru_pages; - if (memcg && is_classzone) + if (memcg && is_classzone) { shrink_slab(sc->gfp_mask, zone_to_nid(zone), memcg, sc->nr_scanned - scanned, lru_pages); + if (reclaim_state) { + sc->nr_reclaimed += + reclaim_state->reclaimed_slab; + reclaim_state->reclaimed_slab = 0; + } + } + /* * Direct reclaim and kswapd have to scan all memory * cgroups to fulfill the overall scan target for the @@ -2467,14 +2474,16 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc, * Shrink the slab caches in the same proportion that * the eligible LRU pages were scanned. */ - if (global_reclaim(sc) && is_classzone) + if (global_reclaim(sc) && is_classzone) { shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL, sc->nr_scanned - nr_scanned, zone_lru_pages); - if (reclaim_state) { - sc->nr_reclaimed += reclaim_state->reclaimed_slab; - reclaim_state->reclaimed_slab = 0; + if (reclaim_state) { + sc->nr_reclaimed += + reclaim_state->reclaimed_slab; + reclaim_state->reclaimed_slab = 0; + } } vmpressure(sc->gfp_mask, sc->target_mem_cgroup, -- 2.6.1