From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AF12C3A59B for ; Fri, 30 Aug 2019 23:04:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5A8082343B for ; Fri, 30 Aug 2019 23:04:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="deO+bEua" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5A8082343B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 10EA36B0010; Fri, 30 Aug 2019 19:04:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0BE776B0266; Fri, 30 Aug 2019 19:04:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ECD216B0269; Fri, 30 Aug 2019 19:04:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0152.hostedemail.com [216.40.44.152]) by kanga.kvack.org (Postfix) with ESMTP id C5AC06B0010 for ; Fri, 30 Aug 2019 19:04:52 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 664E5AC18 for ; Fri, 30 Aug 2019 23:04:52 +0000 (UTC) X-FDA: 75880626024.24.rod34_2a7fc28b42146 X-HE-Tag: rod34_2a7fc28b42146 X-Filterd-Recvd-Size: 4014 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf38.hostedemail.com (Postfix) with ESMTP for ; Fri, 30 Aug 2019 23:04:51 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7DD7F23711; Fri, 30 Aug 2019 23:04:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567206290; bh=UXJ0EujneT5XTD+VEOHzRwZiNEM6Ozy7IvUxmJ84Ss0=; h=Date:From:To:Subject:From; b=deO+bEuaY/vYxRu7ptSfseS0bM0ON8jajgkY0hHge83QK1xsI4nmR2qvffjL3NC49 Ig6hejvM2CG7fNRB6nhLbD7cl58dVyKOCTXQoXYqC/37wBpm7w5A1bR/JQu+/SULAA nlR3EpwX261GQ0q1VerMT8zhwq2M1ynEdknqi9D8= Date: Fri, 30 Aug 2019 16:04:50 -0700 From: akpm@linux-foundation.org To: akpm@linux-foundation.org, hannes@cmpxchg.org, hdanton@sina.com, laoar.shao@gmail.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, promarbler14@gmail.com, torvalds@linux-foundation.org, yang.shi@linux.alibaba.com Subject: [patch 6/7] mm, memcg: do not set reclaim_state on soft limit reclaim Message-ID: <20190830230450.zHIGf1pKy%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Michal Hocko Subject: mm, memcg: do not set reclaim_state on soft limit reclaim Adric Blake has noticed[1] the following warning: [38491.963105] WARNING: CPU: 7 PID: 175 at mm/vmscan.c:245 set_task_reclaim_state+0x1e/0x40 [...] [38491.963239] Call Trace: [38491.963246] mem_cgroup_shrink_node+0x9b/0x1d0 [38491.963250] mem_cgroup_soft_limit_reclaim+0x10c/0x3a0 [38491.963254] balance_pgdat+0x276/0x540 [38491.963258] kswapd+0x200/0x3f0 [38491.963261] ? wait_woken+0x80/0x80 [38491.963265] kthread+0xfd/0x130 [38491.963267] ? balance_pgdat+0x540/0x540 [38491.963269] ? kthread_park+0x80/0x80 [38491.963273] ret_from_fork+0x35/0x40 [38491.963276] ---[ end trace 727343df67b2398a ]--- which tells us that soft limit reclaim is about to overwrite the reclaim_state configured up in the call chain (kswapd in this case but the direct reclaim is equally possible). This means that reclaim stats would get misleading once the soft reclaim returns and another reclaim is done. Fix the warning by dropping set_task_reclaim_state from the soft reclaim which is always called with reclaim_state set up. [1] http://lkml.kernel.org/r/CAE1jjeePxYPvw1mw2B3v803xHVR_BNnz0hQUY_JDMN8ny29M6w@mail.gmail.com Link: http://lkml.kernel.org/r/20190828071808.20410-1-mhocko@kernel.org Signed-off-by: Michal Hocko Reported-by: Adric Blake Acked-by: Yafang Shao Acked-by: Yang Shi Cc: Johannes Weiner Cc: Hillf Danton Signed-off-by: Andrew Morton --- mm/vmscan.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/vmscan.c~mm-memcg-do-not-set-reclaim_state-on-soft-limit-reclaim +++ a/mm/vmscan.c @@ -3220,6 +3220,7 @@ unsigned long try_to_free_pages(struct z #ifdef CONFIG_MEMCG +/* Only used by soft limit reclaim. Do not reuse for anything else. */ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg, gfp_t gfp_mask, bool noswap, pg_data_t *pgdat, @@ -3235,7 +3236,8 @@ unsigned long mem_cgroup_shrink_node(str }; unsigned long lru_pages; - set_task_reclaim_state(current, &sc.reclaim_state); + WARN_ON_ONCE(!current->reclaim_state); + sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) | (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK); @@ -3253,7 +3255,6 @@ unsigned long mem_cgroup_shrink_node(str trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed); - set_task_reclaim_state(current, NULL); *nr_scanned = sc.nr_scanned; return sc.nr_reclaimed; _