From: Hugh Dickins <hughd@google.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch 03/11] mm: shmem: do not try to uncharge known swapcache pages
Date: Mon, 9 Jul 2012 13:37:39 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1207091311300.1842@eggly.anvils> (raw)
In-Reply-To: <20120709144657.GF4627@tiehlicka.suse.cz>
On Mon, 9 Jul 2012, Michal Hocko wrote:
>
> Maybe I am missing something but who does the uncharge from:
> shmem_unuse
> mem_cgroup_cache_charge
> shmem_unuse_inode
> shmem_add_to_page_cache
There isn't any special uncharge for shmem_unuse(): once the swapcache
page is matched up with its memcg, it will get uncharged by one of the
usual routes to swapcache_free() when the page is freed: maybe in the
call from __remove_mapping(), maybe when free_page_and_swap_cache()
ends up calling it.
Perhaps you're worrying about error (or unfound) paths in shmem_unuse()?
By the time we make the charge, we know for sure that it's a shmem page,
and make the charge appropriately; in racy cases it might get uncharged
again in the delete_from_swap_cache(). Can the unfound case occur these
days? I'd have to think more deeply to answer that, but the charge will
not go missing.
Hugh
WARNING: multiple messages have this Message-ID (diff)
From: Hugh Dickins <hughd@google.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [patch 03/11] mm: shmem: do not try to uncharge known swapcache pages
Date: Mon, 9 Jul 2012 13:37:39 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1207091311300.1842@eggly.anvils> (raw)
In-Reply-To: <20120709144657.GF4627@tiehlicka.suse.cz>
On Mon, 9 Jul 2012, Michal Hocko wrote:
>
> Maybe I am missing something but who does the uncharge from:
> shmem_unuse
> mem_cgroup_cache_charge
> shmem_unuse_inode
> shmem_add_to_page_cache
There isn't any special uncharge for shmem_unuse(): once the swapcache
page is matched up with its memcg, it will get uncharged by one of the
usual routes to swapcache_free() when the page is freed: maybe in the
call from __remove_mapping(), maybe when free_page_and_swap_cache()
ends up calling it.
Perhaps you're worrying about error (or unfound) paths in shmem_unuse()?
By the time we make the charge, we know for sure that it's a shmem page,
and make the charge appropriately; in racy cases it might get uncharged
again in the delete_from_swap_cache(). Can the unfound case occur these
days? I'd have to think more deeply to answer that, but the charge will
not go missing.
Hugh
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next prev parent reply other threads:[~2012-07-09 20:38 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-05 0:44 [patch 00/11] mm: memcg: charge/uncharge improvements Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-05 0:44 ` [patch 01/11] mm: memcg: fix compaction/migration failing due to memcg limits Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:27 ` Kamezawa Hiroyuki
2012-07-09 2:27 ` Kamezawa Hiroyuki
2012-07-09 2:27 ` Kamezawa Hiroyuki
2012-07-09 14:15 ` Michal Hocko
2012-07-09 14:15 ` Michal Hocko
2012-07-09 14:15 ` Michal Hocko
2012-07-05 0:44 ` [patch 02/11] mm: swapfile: clean up unuse_pte race handling Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:29 ` Kamezawa Hiroyuki
2012-07-09 2:29 ` Kamezawa Hiroyuki
2012-07-09 14:22 ` Michal Hocko
2012-07-09 14:22 ` Michal Hocko
2012-07-09 14:22 ` Michal Hocko
2012-07-05 0:44 ` [patch 03/11] mm: shmem: do not try to uncharge known swapcache pages Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:33 ` Kamezawa Hiroyuki
2012-07-09 2:33 ` Kamezawa Hiroyuki
2012-07-09 14:46 ` Michal Hocko
2012-07-09 14:46 ` Michal Hocko
2012-07-09 20:37 ` Hugh Dickins [this message]
2012-07-09 20:37 ` Hugh Dickins
2012-07-10 17:16 ` Michal Hocko
2012-07-10 17:16 ` Michal Hocko
2012-07-10 17:16 ` Michal Hocko
2012-07-11 18:48 ` Hugh Dickins
2012-07-11 18:48 ` Hugh Dickins
2012-07-11 18:48 ` Hugh Dickins
2012-07-12 13:51 ` Michal Hocko
2012-07-12 13:51 ` Michal Hocko
2012-07-09 20:11 ` Hugh Dickins
2012-07-09 20:11 ` Hugh Dickins
2012-07-09 20:11 ` Hugh Dickins
2012-07-05 0:44 ` [patch 04/11] mm: memcg: push down PageSwapCache check into uncharge entry functions Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:42 ` Kamezawa Hiroyuki
2012-07-09 2:42 ` Kamezawa Hiroyuki
2012-07-09 2:42 ` Kamezawa Hiroyuki
2012-07-09 7:36 ` Johannes Weiner
2012-07-09 7:36 ` Johannes Weiner
2012-07-09 7:36 ` Johannes Weiner
2012-07-09 15:02 ` Michal Hocko
2012-07-09 15:02 ` Michal Hocko
2012-07-09 15:02 ` Michal Hocko
2012-07-05 0:44 ` [patch 05/11] mm: memcg: only check for PageSwapCache when uncharging anon Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:49 ` Kamezawa Hiroyuki
2012-07-09 2:49 ` Kamezawa Hiroyuki
2012-07-09 2:49 ` Kamezawa Hiroyuki
2012-07-09 15:05 ` Michal Hocko
2012-07-09 15:05 ` Michal Hocko
2012-07-05 0:44 ` [patch 06/11] mm: memcg: move swapin charge functions above callsites Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:50 ` Kamezawa Hiroyuki
2012-07-09 2:50 ` Kamezawa Hiroyuki
2012-07-09 2:50 ` Kamezawa Hiroyuki
2012-07-09 15:10 ` Michal Hocko
2012-07-09 15:10 ` Michal Hocko
2012-07-05 0:44 ` [patch 07/11] mm: memcg: remove unneeded shmem charge type Johannes Weiner
2012-07-05 0:44 ` Johannes Weiner
2012-07-09 2:51 ` Kamezawa Hiroyuki
2012-07-09 2:51 ` Kamezawa Hiroyuki
2012-07-09 15:17 ` Michal Hocko
2012-07-09 15:17 ` Michal Hocko
2012-07-09 15:17 ` Michal Hocko
2012-07-05 0:45 ` [patch 08/11] mm: memcg: remove needless !mm fixup to init_mm when charging Johannes Weiner
2012-07-05 0:45 ` Johannes Weiner
2012-07-09 2:53 ` Kamezawa Hiroyuki
2012-07-09 2:53 ` Kamezawa Hiroyuki
2012-07-09 15:20 ` Michal Hocko
2012-07-09 15:20 ` Michal Hocko
2012-07-09 15:20 ` Michal Hocko
2012-07-10 6:10 ` Wanpeng Li
2012-07-10 6:10 ` Wanpeng Li
2012-07-10 6:10 ` Wanpeng Li
2012-07-10 6:21 ` Michal Hocko
2012-07-10 6:21 ` Michal Hocko
2012-07-10 6:21 ` Michal Hocko
2012-07-10 6:54 ` Wanpeng Li
2012-07-10 6:54 ` Wanpeng Li
2012-07-10 16:22 ` Michal Hocko
2012-07-10 16:22 ` Michal Hocko
2012-07-10 16:22 ` Michal Hocko
2012-07-05 0:45 ` [patch 09/11] mm: memcg: split swapin charge function into private and public part Johannes Weiner
2012-07-05 0:45 ` Johannes Weiner
2012-07-09 2:55 ` Kamezawa Hiroyuki
2012-07-09 2:55 ` Kamezawa Hiroyuki
2012-07-09 2:55 ` Kamezawa Hiroyuki
2012-07-09 15:28 ` Michal Hocko
2012-07-09 15:28 ` Michal Hocko
2012-07-09 15:28 ` Michal Hocko
2012-07-05 0:45 ` [patch 10/11] mm: memcg: only check swap cache pages for repeated charging Johannes Weiner
2012-07-05 0:45 ` Johannes Weiner
2012-07-09 3:26 ` Kamezawa Hiroyuki
2012-07-09 3:26 ` Kamezawa Hiroyuki
2012-07-09 15:32 ` Michal Hocko
2012-07-09 15:32 ` Michal Hocko
2012-07-05 0:45 ` [patch 11/11] mm: memcg: only check anon swapin page charges for swap cache Johannes Weiner
2012-07-05 0:45 ` Johannes Weiner
2012-07-09 3:44 ` Kamezawa Hiroyuki
2012-07-09 3:44 ` Kamezawa Hiroyuki
2012-07-09 3:44 ` Kamezawa Hiroyuki
2012-07-09 15:34 ` Michal Hocko
2012-07-09 15:34 ` Michal Hocko
2012-07-09 15:34 ` Michal Hocko
2012-07-09 15:35 ` [patch 00/11] mm: memcg: charge/uncharge improvements Michal Hocko
2012-07-09 15:35 ` Michal Hocko
2012-07-09 15:35 ` Michal Hocko
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