From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754304AbdA0IO2 (ORCPT ); Fri, 27 Jan 2017 03:14:28 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:33620 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754256AbdA0IO1 (ORCPT ); Fri, 27 Jan 2017 03:14:27 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org D99AA60A02 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=vinmenon@codeaurora.org From: Vinayak Menon To: akpm@linux-foundation.org, hannes@cmpxchg.org, mgorman@techsingularity.net, vbabka@suse.cz, mhocko@suse.com, riel@redhat.com, vdavydov.dev@gmail.com, anton.vorontsov@linaro.org, minchan@kernel.org, shashim@codeaurora.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vinayak Menon Subject: [PATCH 1/2 v2] mm: vmscan: do not pass reclaimed slab to vmpressure Date: Fri, 27 Jan 2017 13:43:36 +0530 Message-Id: <1485504817-3124-1-git-send-email-vinmenon@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is noticed that during a global reclaim the memory reclaimed via shrinking the slabs can sometimes result in reclaimed pages being greater than the scanned pages in shrink_node. When this is passed to vmpressure, the unsigned arithmetic results in the pressure value to be huge, thus resulting in a critical event being sent to root cgroup. While this can be fixed by underflow checks in vmpressure, adding reclaimed slab without a corresponding increment of nr_scanned results in incorrect vmpressure reporting. So do not consider reclaimed slab pages in vmpressure calculation. Signed-off-by: Vinayak Menon --- mm/vmscan.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 947ab6f..37c4486 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2594,16 +2594,16 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc) sc->nr_scanned - nr_scanned, node_lru_pages); - if (reclaim_state) { - sc->nr_reclaimed += reclaim_state->reclaimed_slab; - reclaim_state->reclaimed_slab = 0; - } - /* Record the subtree's reclaim efficiency */ vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true, sc->nr_scanned - nr_scanned, sc->nr_reclaimed - nr_reclaimed); + if (reclaim_state) { + sc->nr_reclaimed += reclaim_state->reclaimed_slab; + reclaim_state->reclaimed_slab = 0; + } + if (sc->nr_reclaimed - nr_reclaimed) reclaimable = true; -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation