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=-0.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 856BFC3A5A6 for ; Tue, 27 Aug 2019 11:52:01 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 44A0A2184D for ; Tue, 27 Aug 2019 11:52:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="S8Ra+hm/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 44A0A2184D 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 D3F7A6B0008; Tue, 27 Aug 2019 07:52:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id CEF626B000A; Tue, 27 Aug 2019 07:52:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BDE686B000C; Tue, 27 Aug 2019 07:52:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0032.hostedemail.com [216.40.44.32]) by kanga.kvack.org (Postfix) with ESMTP id 997CD6B0008 for ; Tue, 27 Aug 2019 07:52:00 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 3ECB352D7 for ; Tue, 27 Aug 2019 11:52:00 +0000 (UTC) X-FDA: 75868044000.01.curve20_68c52200df623 X-HE-Tag: curve20_68c52200df623 X-Filterd-Recvd-Size: 4798 Received: from mail-io1-f65.google.com (mail-io1-f65.google.com [209.85.166.65]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Tue, 27 Aug 2019 11:51:59 +0000 (UTC) Received: by mail-io1-f65.google.com with SMTP id t3so45464172ioj.12 for ; Tue, 27 Aug 2019 04:51:59 -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=PpAYaVqXIDzzWCYZGUrTDP575lSiv4NfiGUR8GS0TG4=; b=S8Ra+hm/VktuuLKgmXx4Led4HSI634Wn+GEvQh1Ot6rcatTA2Y/lNWklJLiqI0P8Pt 6OqGGTKtYOiza2E6DKy1zWfQrnZyZBckWn57+KtTa7FXZugmLUD1NSsaEY28WF9jnf+u YI07oKFCtQnfaYOmxVsmwtRfn2wttE1TyKmNRUs42e7y338D4atqXpOhzvQQ6+WjZOmN wDfenOnM8zUKCRtRzzx+nU1iOUMoLtY27sIBfXsOS09D5fJkDzUipmkxzF/eX8Y51kwt aR2//zKKXBf2DJVHcJCI7WM6DgqqrqEX+kGO2T4Q/vVxJnukkJRPxV33X0arScjPvN/i 9fPA== 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=PpAYaVqXIDzzWCYZGUrTDP575lSiv4NfiGUR8GS0TG4=; b=SlVOawlOKyxpfyXjiVtdpTOSdDzUNZVA88HRAqgvxi2tb79VAWi7xNmqqTt4FgXEx2 IwfQBFShgS/WZOvWOOB4G2KBtD0drvJbdua43IoweJqIL4hUljnjDeNTM6X0kJxe9teX 7K4u2e8eMluOG72P5CFeTiK/5W9NU5d4fZjE4hRvGhEDJlF9bhy7TT/qLfEm1KAXiX6i KdzW4Vh3Qy05F4ZU7IgsT2kPf+75yxzA9kynvfOihzv5XPqlgvdjE3JGWAEFVANYOk80 pURtRe0b/jJtvVZz7Ant6Q/bfyo5vBrOF5we7oru0Xzf16DUnsp8JebQYEA8q0ZxmuL4 KD9w== X-Gm-Message-State: APjAAAUmkexSiRJ/Syd3pv4EPzPyqQUjDSkcsnUFxBKhXpxxK0AlXYxn aJvs0FwR/cs5jYlTSU+oyVnXkwglYRwTyC0cXqc= X-Google-Smtp-Source: APXvYqy4z6BwI8sXMDX6dDDYBASFKNHi7rHKynHJNOAjqWi131ChcpUvAK5PPT7mm0ZbhEe5qGwgD/G3K4PRdClYHp0= X-Received: by 2002:a02:495:: with SMTP id 143mr22026989jab.94.1566906719117; Tue, 27 Aug 2019 04:51:59 -0700 (PDT) MIME-Version: 1.0 References: <20190824130516.2540-1-hdanton@sina.com> In-Reply-To: <20190824130516.2540-1-hdanton@sina.com> From: Yafang Shao Date: Tue, 27 Aug 2019 19:51:23 +0800 Message-ID: Subject: Re: WARNINGs in set_task_reclaim_state with memory cgroup andfullmemory usage To: Hillf Danton Cc: Adric Blake , Andrew Morton , Kirill Tkhai , Johannes Weiner , Michal Hocko , Daniel Jordan , Yang Shi , Mel Gorman , Linux MM , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000003, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Aug 24, 2019 at 9:05 PM Hillf Danton wrote: > > > On Sat, 24 Aug 2019 16:15:38 +0800 Yafang Shao wrote: > > > > The memcg soft reclaim is called from kswapd reclam path and direct > > reclaim path, > > so why not pass the scan_control from the callsite in these two > > reclaim paths and use it in memcg soft reclaim ? > > Seems there's no specially reason that we must introduce a new > > scan_control here. > > > To protect memcg from being over reclaimed? Not only this, but also makes the reclaim path more clear. > Victim memcg is selected one after another in a fair way, and punished > by reclaiming one memcg a round no more than nr_to_reclaim == > SWAP_CLUSTER_MAX pages. And so is the flip-flop from global to memcg > reclaiming. We can see similar protection activities in > commit a394cb8ee632 ("memcg,vmscan: do not break out targeted reclaim > without reclaimed pages") and > commit 2bb0f34fe3c1 ("mm: vmscan: do not iterate all mem cgroups for > global direct reclaim"). > > No preference seems in either way except for retaining > nr_to_reclaim == SWAP_CLUSTER_MAX and target_mem_cgroup == memcg. Setting target_mem_cgroup here may be a very subtle change for subsequent processing. Regarding retraining nr_to_reclaim == SWAP_CLUSTER_MAX, it may not proper for direct reclaim, that may cause some stall if we iterate all memcgs here. > > > > I have checked the hisotry why this order check is introduced here. > > The first commit is 4e41695356fb ("memory controller: soft limit > > reclaim on contention"), > > but it didn't explained why. > > At the first glance it is reasonable to remove it, but we should > > understand why it was introduced at the first place. > > Reclaiming order can not make much sense in soft-limit reclaiming > under the current protection. > > Thanks to Adric Blake again. > > Hillf >