From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id C8DC36B0038 for ; Fri, 27 Jan 2017 03:14:10 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id z67so343115346pgb.0 for ; Fri, 27 Jan 2017 00:14:10 -0800 (PST) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.29.96]) by mx.google.com with ESMTPS id d67si3751792pfe.39.2017.01.27.00.14.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 27 Jan 2017 00:14:10 -0800 (PST) From: 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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 -- 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/ . Don't email: email@kvack.org