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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 84086C3A5A4 for ; Tue, 27 Aug 2019 11:44:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 169672184D for ; Tue, 27 Aug 2019 11:44:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="k0fxmZy5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 169672184D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7EDCC6B0005; Tue, 27 Aug 2019 07:44:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 79F9F6B0006; Tue, 27 Aug 2019 07:44:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6B56E6B0007; Tue, 27 Aug 2019 07:44:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0170.hostedemail.com [216.40.44.170]) by kanga.kvack.org (Postfix) with ESMTP id 4849E6B0005 for ; Tue, 27 Aug 2019 07:44:27 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id DF8156D93 for ; Tue, 27 Aug 2019 11:44:26 +0000 (UTC) X-FDA: 75868024932.23.map62_26ca370025203 X-HE-Tag: map62_26ca370025203 X-Filterd-Recvd-Size: 6637 Received: from mail-io1-f67.google.com (mail-io1-f67.google.com [209.85.166.67]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Tue, 27 Aug 2019 11:44:26 +0000 (UTC) Received: by mail-io1-f67.google.com with SMTP id z3so45593315iog.0 for ; Tue, 27 Aug 2019 04:44:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=B6JKwNjAX9OFJ5Xpu3hN1K2seR+5vG6lZdDfWoSwR4Y=; b=k0fxmZy5mkRO2ooZzqehi9uB3sSTOy7DeHxXcX76sPz5P/kJMkE6dE/KO8756/7LFu LzwR+VnWhUMMBLuZIOIOaQPqqt8Dt2/ANod0nT4sL8th5LprN+dh8fGsh89uWp960+lM 7rjYfVHHjGi3yVT9YbaPA2DuFoYbh1ERUyFbLHE47q6uKgd8liYwqsEX9LdcH+jal+nB ajXw7FAJhUGoWC8BrTi6s/6AbFg2tBHUEd/mAVCCeqS8ZjOJgfSo9PMXyoL29h+3h/rA FdjkoZveFpVmVRok2wvo/sI5+M9WmjA/0+nYxuheAtFKAnVph2kVxMd04vwiVyKsvwwo hU7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=B6JKwNjAX9OFJ5Xpu3hN1K2seR+5vG6lZdDfWoSwR4Y=; b=tK4IA5Vqce/13TVByWhdl8wm2bZwhpSa79yJrzztcyRHCiBMls480bblp2m855KCyn CEFI1jRGbdK0QBUtONG7Th6RfX7mFqCNbO3jvCDZjSA/UEnNJ0YFgWUccgEGLtUTnu7p YYDs2T9hFKPX3WOrgNVgR2KIqbLx1xw8/YWTQd5JI6rYPAGE+Iyc9aJnKB4AOtvsC+Wz tR1RX1VaZs26REn8y8En/yHtRuTzg8y4EEEhcgJLLuW8gpF8GQkN5yNJs53uWgVKCxHC gCCrV9O6/C3l6Mria+0vZc2L54gtGjMIZBqn1SyxuFzF8oRPFm73Sd2CaV1zK0w1C3HU vuYQ== X-Gm-Message-State: APjAAAVDIKaEFUvjx0Ww9LJ7i5qa5li7R8bWYjgRXenn2l7NVCZXw4r4 3b+QK3zH1S2y2rVqnZR6xi7hMgJKmJQtjjhUaxA= X-Google-Smtp-Source: APXvYqwUjF2i+jobmTD/+17nn+qZUSU8T53snEGwU4Uiy0N1tHQF84x+e/mm0P637mHevNeqThe8tS+Ho+AmsZuexSg= X-Received: by 2002:a6b:cac2:: with SMTP id a185mr17954858iog.142.1566906265777; Tue, 27 Aug 2019 04:44:25 -0700 (PDT) MIME-Version: 1.0 References: <20190826105521.GF7538@dhcp22.suse.cz> <20190827104313.GW7538@dhcp22.suse.cz> In-Reply-To: <20190827104313.GW7538@dhcp22.suse.cz> From: Yafang Shao Date: Tue, 27 Aug 2019 19:43:49 +0800 Message-ID: Subject: Re: WARNINGs in set_task_reclaim_state with memory cgroup and full memory usage To: Michal Hocko Cc: Yang Shi , Adric Blake , Andrew Morton , Kirill Tkhai , Johannes Weiner , Daniel Jordan , Mel Gorman , Linux MM , LKML Content-Type: text/plain; charset="UTF-8" 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: On Tue, Aug 27, 2019 at 6:43 PM Michal Hocko wrote: > > If there are no objection to the patch I will post it as a standalong > one. I have no objection to your patch. It could fix the issue. I still think that it is not proper to use a new scan_control here as it breaks the global reclaim context. This context switch from global reclaim to memcg reclaim is very subtle change to the subsequent processing, that may cause some unexpected behavior. Anyway, we can send this patch as a standalong one. Feel free to add: Acked-by: Yafang Shao > > On Mon 26-08-19 12:55:21, Michal Hocko wrote: > > From 59d128214a62bf2d83c2a2a9cde887b4817275e7 Mon Sep 17 00:00:00 2001 > > From: Michal Hocko > > Date: Mon, 26 Aug 2019 12:43:15 +0200 > > Subject: [PATCH] mm, memcg: do not set reclaim_state on soft limit reclaim > > > > Adric Blake has noticed 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. > > > > Reported-by: Adric Blake > > Signed-off-by: Michal Hocko > > --- > > mm/vmscan.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index c77d1e3761a7..a6c5d0b28321 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -3220,6 +3220,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, > > > > #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(struct mem_cgroup *memcg, > > }; > > 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(struct mem_cgroup *memcg, > > > > 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; > > -- > > 2.20.1 > > > > -- > > Michal Hocko > > SUSE Labs > > -- > Michal Hocko > SUSE Labs