From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932504AbcA2QoQ (ORCPT ); Fri, 29 Jan 2016 11:44:16 -0500 Received: from gum.cmpxchg.org ([85.214.110.215]:55556 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753184AbcA2QoO (ORCPT ); Fri, 29 Jan 2016 11:44:14 -0500 Date: Fri, 29 Jan 2016 11:43:53 -0500 From: Johannes Weiner To: Vladimir Davydov Cc: Andrew Morton , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 1/5] mm: memcontrol: generalize locking for the page->mem_cgroup binding Message-ID: <20160129164353.GA8845@cmpxchg.org> References: <1453842006-29265-1-git-send-email-hannes@cmpxchg.org> <1453842006-29265-2-git-send-email-hannes@cmpxchg.org> <20160127143045.GA9623@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160127143045.GA9623@esperanza> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 27, 2016 at 05:30:45PM +0300, Vladimir Davydov wrote: > On Tue, Jan 26, 2016 at 04:00:02PM -0500, Johannes Weiner wrote: > > > @@ -683,17 +683,17 @@ int __set_page_dirty_buffers(struct page *page) > > } while (bh != head); > > } > > /* > > - * Use mem_group_begin_page_stat() to keep PageDirty synchronized with > > - * per-memcg dirty page counters. > > + * Lock out page->mem_cgroup migration to keep PageDirty > > + * synchronized with per-memcg dirty page counters. > > */ > > - memcg = mem_cgroup_begin_page_stat(page); > > + memcg = lock_page_memcg(page); > > newly_dirty = !TestSetPageDirty(page); > > spin_unlock(&mapping->private_lock); > > > > if (newly_dirty) > > __set_page_dirty(page, mapping, memcg, 1); > > Do we really want to pass memcg to __set_page_dirty and then to > account_page_dirtied, increasing stack/regs usage even in case memory > cgroup is disabled? May be, it'd be better to make > mem_cgroup_update_page_stat take a page instead of a memcg? I'll look into that. It will need changing migration to leave the page->mem_cgroup binding of live pages alone, but that's something worth doing anyway. It's beyond the scope of these patches, though. Thanks