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_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 BE84CC43144 for ; Fri, 29 Jun 2018 09:52:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82C3827CF3 for ; Fri, 29 Jun 2018 09:52:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 82C3827CF3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934753AbeF2JwU (ORCPT ); Fri, 29 Jun 2018 05:52:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:42466 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S934570AbeF2JwF (ORCPT ); Fri, 29 Jun 2018 05:52:05 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 626B9ACF3; Fri, 29 Jun 2018 09:52:01 +0000 (UTC) Date: Fri, 29 Jun 2018 11:52:00 +0200 From: Michal Hocko To: Shakeel Butt Cc: Jan Kara , Andrew Morton , Johannes Weiner , Vladimir Davydov , Jan Kara , Greg Thelen , Amir Goldstein , Roman Gushchin , Alexander Viro , LKML , Cgroups , linux-fsdevel , Linux MM Subject: Re: [PATCH 1/2] fs: fsnotify: account fsnotify metadata to kmemcg Message-ID: <20180629095200.GF13860@dhcp22.suse.cz> References: <20180627191250.209150-1-shakeelb@google.com> <20180627191250.209150-2-shakeelb@google.com> <20180628100253.jscxkw2d6vfhnbo5@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 28-06-18 12:21:26, Shakeel Butt wrote: > On Thu, Jun 28, 2018 at 12:03 PM Jan Kara wrote: > > > > On Wed 27-06-18 12:12:49, Shakeel Butt wrote: > > > A lot of memory can be consumed by the events generated for the huge or > > > unlimited queues if there is either no or slow listener. This can cause > > > system level memory pressure or OOMs. So, it's better to account the > > > fsnotify kmem caches to the memcg of the listener. > > > > > > However the listener can be in a different memcg than the memcg of the > > > producer and these allocations happen in the context of the event > > > producer. This patch introduces remote memcg charging API which the > > > producer can use to charge the allocations to the memcg of the listener. > > > > > > There are seven fsnotify kmem caches and among them allocations from > > > dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and > > > inotify_inode_mark_cachep happens in the context of syscall from the > > > listener. So, SLAB_ACCOUNT is enough for these caches. > > > > > > The objects from fsnotify_mark_connector_cachep are not accounted as they > > > are small compared to the notification mark or events and it is unclear > > > whom to account connector to since it is shared by all events attached to > > > the inode. > > > > > > The allocations from the event caches happen in the context of the event > > > producer. For such caches we will need to remote charge the allocations > > > to the listener's memcg. Thus we save the memcg reference in the > > > fsnotify_group structure of the listener. > > > > > > This patch has also moved the members of fsnotify_group to keep the size > > > same, at least for 64 bit build, even with additional member by filling > > > the holes. > > > > ... > > > > > static int __init fanotify_user_setup(void) > > > { > > > - fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC); > > > + fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, > > > + SLAB_PANIC|SLAB_ACCOUNT); > > > fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC); > > > if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) { > > > fanotify_perm_event_cachep = > > > > Why don't you setup also fanotify_event_cachep and > > fanotify_perm_event_cachep caches with SLAB_ACCOUNT and instead specify > > __GFP_ACCOUNT manually? Otherwise the patch looks good to me. > > > > Hi Jan, IMHO having a visible __GFP_ACCOUNT along with > memalloc_use_memcg() makes the code more explicit and readable that we > want to targeted/remote memcg charging. Agreed. If you had an implicit SLAB_ACCOUNT then you could get inconsistencies when some allocations would get charged to the current task while others would not. -- Michal Hocko SUSE Labs