From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Konstantin Khlebnikov <khlebnikov@openvz.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Ying Han <yinghan@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/10] mm/memcg: remove mem_cgroup_reset_owner
Date: Tue, 21 Feb 2012 18:17:28 +0900 [thread overview]
Message-ID: <20120221181728.3778b1fd.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <alpine.LSU.2.00.1202201534340.23274@eggly.anvils>
On Mon, 20 Feb 2012 15:35:38 -0800 (PST)
Hugh Dickins <hughd@google.com> wrote:
> With mem_cgroup_reset_uncharged_to_root() now making sure that freed
> pages point to root_mem_cgroup (instead of to a stale and perhaps
> long-deleted memcg), we no longer need to initialize page memcg to
> root in those odd places which put a page on lru before charging.
> Delete mem_cgroup_reset_owner().
>
> But: we have no init_page_cgroup() nowadays (and even when we had,
> it was called before root_mem_cgroup had been allocated); so until
> a struct page has once entered the memcg lru cycle, its page_cgroup
> ->mem_cgroup will be NULL instead of root_mem_cgroup.
>
> That could be fixed by reintroducing init_page_cgroup(), and ordering
> properly: in future we shall probably want root_mem_cgroup in kernel
> bss or data like swapper_space; but let's not get into that right now.
>
> Instead allow for this in page_relock_lruvec(): treating NULL as
> root_mem_cgroup, and correcting pc->mem_cgroup before going further.
>
> What? Before even taking the zone->lru_lock? Is that safe?
> Yes, because compaction and lumpy reclaim use __isolate_lru_page(),
> which refuses unless it sees PageLRU - which may be cleared at any
> instant, but we only need it to have been set once in the past for
> pc->mem_cgroup to be initialized properly.
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
Ok, this seems to be much better than current reset_owner().
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Thanks,
-Kame
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next prev parent reply other threads:[~2012-02-21 9:18 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-20 23:26 [PATCH 0/10] mm/memcg: per-memcg per-zone lru locking Hugh Dickins
2012-02-20 23:28 ` [PATCH 1/10] mm/memcg: scanning_global_lru means mem_cgroup_disabled Hugh Dickins
2012-02-21 8:03 ` KAMEZAWA Hiroyuki
2012-02-20 23:29 ` [PATCH 2/10] mm/memcg: move reclaim_stat into lruvec Hugh Dickins
2012-02-21 8:05 ` KAMEZAWA Hiroyuki
2012-02-20 23:30 ` [PATCH 3/10] mm/memcg: add zone pointer " Hugh Dickins
2012-02-21 8:08 ` KAMEZAWA Hiroyuki
2012-02-20 23:32 ` [PATCH 4/10] mm/memcg: apply add/del_page to lruvec Hugh Dickins
2012-02-21 8:20 ` KAMEZAWA Hiroyuki
2012-02-21 22:25 ` Hugh Dickins
2012-02-20 23:33 ` [PATCH 5/10] mm/memcg: introduce page_relock_lruvec Hugh Dickins
2012-02-21 8:38 ` KAMEZAWA Hiroyuki
2012-02-21 22:36 ` Hugh Dickins
2012-02-20 23:34 ` [PATCH 6/10] mm/memcg: take care over pc->mem_cgroup Hugh Dickins
2012-02-21 5:55 ` Konstantin Khlebnikov
2012-02-21 19:37 ` Hugh Dickins
2012-02-21 20:40 ` Konstantin Khlebnikov
2012-02-21 22:05 ` Hugh Dickins
2012-02-21 6:05 ` Konstantin Khlebnikov
2012-02-21 20:00 ` Hugh Dickins
2012-02-21 9:13 ` KAMEZAWA Hiroyuki
2012-02-21 23:03 ` Hugh Dickins
2012-02-22 4:05 ` Konstantin Khlebnikov
2012-02-20 23:35 ` [PATCH 7/10] mm/memcg: remove mem_cgroup_reset_owner Hugh Dickins
2012-02-21 9:17 ` KAMEZAWA Hiroyuki [this message]
2012-02-20 23:36 ` [PATCH 8/10] mm/memcg: nest lru_lock inside page_cgroup lock Hugh Dickins
2012-02-21 9:48 ` KAMEZAWA Hiroyuki
2012-02-20 23:38 ` [PATCH 9/10] mm/memcg: move lru_lock into lruvec Hugh Dickins
2012-02-21 7:08 ` Konstantin Khlebnikov
2012-02-21 20:12 ` Hugh Dickins
2012-02-21 21:35 ` Konstantin Khlebnikov
2012-02-21 22:12 ` Hugh Dickins
2012-02-22 3:43 ` Konstantin Khlebnikov
2012-02-22 6:09 ` Hugh Dickins
2012-02-23 14:21 ` Konstantin Khlebnikov
2012-02-20 23:39 ` [PATCH 10/10] mm/memcg: per-memcg per-zone lru locking Hugh Dickins
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