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=-2.5 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 4DF44C432C0 for ; Wed, 27 Nov 2019 12:32:30 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 154F12075C for ; Wed, 27 Nov 2019 12:32:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 154F12075C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9AE976B039E; Wed, 27 Nov 2019 07:32:29 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 95F866B039F; Wed, 27 Nov 2019 07:32:29 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 850036B03A1; Wed, 27 Nov 2019 07:32:29 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0198.hostedemail.com [216.40.44.198]) by kanga.kvack.org (Postfix) with ESMTP id 713DF6B039E for ; Wed, 27 Nov 2019 07:32:29 -0500 (EST) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 314A3181AEF15 for ; Wed, 27 Nov 2019 12:32:29 +0000 (UTC) X-FDA: 76201995618.13.rings86_8a0f482982303 X-HE-Tag: rings86_8a0f482982303 X-Filterd-Recvd-Size: 3375 Received: from mail-wr1-f65.google.com (mail-wr1-f65.google.com [209.85.221.65]) by imf13.hostedemail.com (Postfix) with ESMTP for ; Wed, 27 Nov 2019 12:32:28 +0000 (UTC) Received: by mail-wr1-f65.google.com with SMTP id z3so26458841wru.3 for ; Wed, 27 Nov 2019 04:32:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=APAHGrPXLQYqK4XEoTpL2DzSySkqv8Fb1fkOTesm7KY=; b=ODJYsl4IGNngEec80a5UnXImUwonrwS431vy913Uhgu/ijb9bXAsqLHY9eLbu9yTCZ H/YjYfKXEEZlnnCoNrwOEbLObuakkOzSoTjCrXwWaAEXzAn6VvatpkwhtA/FpXR33QWu z6ajcgRA7tdrWMlN4S4WIy65eq6hFAqUkKAcvdvEDUIqF8Ua78j2IUBDer7toQ2XxOku TfBtMBHVj0m4DsmTaghMV7044f6e4QuqhyJwLQ7oKS/G+lnyAoQ9dW7HrET5aBK75Ii0 20idzcsV124eMB4atFcQ6Sj++Ug3IIgi1aaacvQkncexQAGUr/526hyqDzXtvAqavTDJ zyYA== X-Gm-Message-State: APjAAAUqSah0BzXPO83i+2M8iai+FQD2UhXdaawjy9OhZv6kacI/gNJ/ UmJfhOiMr9KVFYVm6OGZIJ8= X-Google-Smtp-Source: APXvYqxfKgQ5PfmLC6R8aUvg0wAMhGCvN28Tabbxnu2utp0rEv/IP2wvtLrgZvqhCyzrvsU3FB+Yjw== X-Received: by 2002:adf:f3d0:: with SMTP id g16mr22568717wrp.2.1574857947424; Wed, 27 Nov 2019 04:32:27 -0800 (PST) Received: from localhost (prg-ext-pat.suse.com. [213.151.95.130]) by smtp.gmail.com with ESMTPSA id b14sm6614061wmj.18.2019.11.27.04.32.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Nov 2019 04:32:26 -0800 (PST) Date: Wed, 27 Nov 2019 13:32:25 +0100 From: Michal Hocko To: Roman Gushchin Cc: "linux-mm@kvack.org" , Andrew Morton , Johannes Weiner , "linux-kernel@vger.kernel.org" , Kernel Team , Christian Borntraeger , "stable@vger.kernel.org" Subject: Re: [PATCH] mm: memcg/slab: wait for !root kmem_cache refcnt killing on root kmem_cache destruction Message-ID: <20191127123225.GR20912@dhcp22.suse.cz> References: <20191125185453.278468-1-guro@fb.com> <20191126092918.GB20912@dhcp22.suse.cz> <20191126184135.GA66034@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191126184135.GA66034@localhost.localdomain> User-Agent: Mutt/1.10.1 (2018-07-13) 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 26-11-19 18:41:41, Roman Gushchin wrote: > On Tue, Nov 26, 2019 at 10:29:18AM +0100, Michal Hocko wrote: > > On Mon 25-11-19 10:54:53, Roman Gushchin wrote: [...] > > > So in a rare case when not all children kmem_caches are destroyed > > > at the moment when the root kmem_cache is about to be gone, we need > > > to wait another rcu grace period before destroying the root > > > kmem_cache. > > > > Could you explain how rare this really is please? > > It seems that we don't destroy root kmem_caches with enabled memcg > accounting that often, but maybe I'm biased here. So this happens each time a root kmem_cache is destroyed? Which would imply that only dynamically created ones? -- Michal Hocko SUSE Labs