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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 3CFEAC2BC11 for ; Fri, 11 Sep 2020 22:40:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA18E20770 for ; Fri, 11 Sep 2020 22:40:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="wWvQJhNN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725950AbgIKWkj (ORCPT ); Fri, 11 Sep 2020 18:40:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44954 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbgIKWkf (ORCPT ); Fri, 11 Sep 2020 18:40:35 -0400 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 269D5C061757 for ; Fri, 11 Sep 2020 15:40:35 -0700 (PDT) Received: by mail-lj1-x243.google.com with SMTP id u4so13711099ljd.10 for ; Fri, 11 Sep 2020 15:40:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=QVD1gZDtb4fovFqzFSv9irG+x3sWgcFoSpx/oNvkoLE=; b=wWvQJhNNIRUX720qs0qN6+3c+1AchsI6qKG/w09Wn7lBRPPTO9VrrYHzLzstivrpb+ 1ntUr9NR+s11KMAsEoV2yW5FVFhWj/UMQzNeUlnXk9b4of6XLFIL95AQZBMFzXDsgEzo 8ufltuCI0KxK+2XTSpc08ZmJ4BoPeH2CA89Y0qQTRX78I9bJtA9NGelq3Hi04uPzbl10 S64Oow+7ks4NSY/8yQlfgPXaZ4/2FgT3F35IJVfVki/Kfv/cF1kjxx/ka43qIKd3OEnz OYSd0D+MUzpFUSRqh8uiUTRNjAgqdPF5kun9fp6XUEaQWHVhOONtBRs7igJUcvMgFnUP eZ3w== 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=QVD1gZDtb4fovFqzFSv9irG+x3sWgcFoSpx/oNvkoLE=; b=dfHxOGrkMPVYJ6xH0Ncixv0FQFGWE3Xr3eW5owiaAiB8dUcNKR71SNJGr+mrLMY9FF sV7t5ZODUBLc2p1+jw0wFbqODt0Thc4/Qwn9tcwSC5JHr7L5HUX4lyt7T2t43WqD+E26 i+okswIKVXlUM0gyA4NweAubsa/g04U/AYchAkh+FmXihFE2kQ6tyCpdwNuxnWmsdMRy AT2DnwMwf9jiMygeE1oZWlzDq0bU7KUwjGoq8/m0e4gh7K8oSDbx1uArUZ49nU9hOlpu K8optaLTal47zo3umtaje+HOHU2Qjo32rsadr2V4RB/pckrERlLpi2rXrFzHcZjnoma7 9WHA== X-Gm-Message-State: AOAM530zRd4+FArOc7vyERlehw4qRpDabifBYLsq1a20No/yQT3BGbcF fzTjzRfyzwsuP7pw6zMfARBBYmkyCY+bs1qD1MeZQw== X-Google-Smtp-Source: ABdhPJxxNqP9whJBEo8PXefOIUInGr92nmFnc34eTFWtLjjf5s45gth3jWS60mVcMNMD5wKHe5/WUmhmwWvm9MNerb8= X-Received: by 2002:a2e:541c:: with SMTP id i28mr1587321ljb.77.1599864031892; Fri, 11 Sep 2020 15:40:31 -0700 (PDT) MIME-Version: 1.0 References: <20200910022435.2773735-1-guro@fb.com> <20200910224309.GB1307870@carbon.dhcp.thefacebook.com> <20200911213402.GB1163084@carbon.dhcp.thefacebook.com> In-Reply-To: <20200911213402.GB1163084@carbon.dhcp.thefacebook.com> From: Shakeel Butt Date: Fri, 11 Sep 2020 15:40:20 -0700 Message-ID: Subject: Re: [PATCH] mm: memcg/slab: fix racy access to page->mem_cgroup in mem_cgroup_from_obj() To: Roman Gushchin Cc: Andrew Morton , Linux MM , Johannes Weiner , Michal Hocko , Kernel Team , LKML , Vlastimil Babka , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 11, 2020 at 2:34 PM Roman Gushchin wrote: > [snip] > > > > Also have you taken a look at [1]? I am still trying to figure out how > > that is possible. > > > > [1] https://lore.kernel.org/lkml/20200901075321.GL4299@shao2-debian/ > > Hm, yeah, it's complicated. At the very first glance it looks like that the > obj_cgroups vector is placed onto the very same page it describes, or at least > it shares the kmem_cache with it, with some bad consequences. Could be something > SLAB-specific, newer saw anything like that with SLUB. > Or maybe it's completely unrelated and has been attributed to this commit > by mistake. > > I've spent several hours running the provided test in a loop, but wasn't > lucky enough to trigger it. Did you try? > Yeah same, no success in reproducing it.