From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Davydov Subject: Re: [PATCH 1/5] mm: memcontrol: generalize locking for the page->mem_cgroup binding Date: Wed, 27 Jan 2016 17:30:45 +0300 Message-ID: <20160127143045.GA9623@esperanza> References: <1453842006-29265-1-git-send-email-hannes@cmpxchg.org> <1453842006-29265-2-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: <1453842006-29265-2-git-send-email-hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Transfer-Encoding: 7bit To: Johannes Weiner Cc: Andrew Morton , Michal Hocko , linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kernel-team-b10kYP2dOMg@public.gmane.org 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? Thanks, Vladimir > > - mem_cgroup_end_page_stat(memcg); > + unlock_page_memcg(memcg); > > if (newly_dirty) > __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);