From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Konstantin Khlebnikov <khlebnikov@openvz.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH next] memcg: fix deadlock by avoiding stat lock when anon
Date: Tue, 28 Feb 2012 21:26:56 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.2.00.1202282125240.4875@eggly.anvils> (raw)
In-Reply-To: <alpine.LSU.2.00.1202282121160.4875@eggly.anvils>
Fix deadlock in "memcg: use new logic for page stat accounting".
page_remove_rmap() first calls mem_cgroup_begin_update_page_stat(),
which may take move_lock_mem_cgroup(), unlocked at the end of
page_remove_rmap() by mem_cgroup_end_update_page_stat().
The PageAnon case never needs to mem_cgroup_dec_page_stat(page,
MEMCG_NR_FILE_MAPPED); but it often needs to mem_cgroup_uncharge_page(),
which does lock_page_cgroup(), while holding that move_lock_mem_cgroup().
Whereas mem_cgroup_move_account() calls move_lock_mem_cgroup() while
holding lock_page_cgroup().
Since mem_cgroup_begin and end are unnecessary here for PageAnon,
simply avoid the deadlock and wasted calls in that case.
Signed-off-by: Hugh Dickins <hughd@google.com>
---
mm/rmap.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- 3.3-rc5-next/mm/rmap.c 2012-02-26 23:51:46.506050210 -0800
+++ linux/mm/rmap.c 2012-02-27 20:25:56.423324211 -0800
@@ -1166,10 +1166,12 @@ void page_add_file_rmap(struct page *pag
*/
void page_remove_rmap(struct page *page)
{
+ bool anon = PageAnon(page);
bool locked;
unsigned long flags;
- mem_cgroup_begin_update_page_stat(page, &locked, &flags);
+ if (!anon)
+ mem_cgroup_begin_update_page_stat(page, &locked, &flags);
/* page still mapped by someone else? */
if (!atomic_add_negative(-1, &page->_mapcount))
goto out;
@@ -1181,7 +1183,7 @@ void page_remove_rmap(struct page *page)
* not if it's in swapcache - there might be another pte slot
* containing the swap entry, but page not yet written to swap.
*/
- if ((!PageAnon(page) || PageSwapCache(page)) &&
+ if ((!anon || PageSwapCache(page)) &&
page_test_and_clear_dirty(page_to_pfn(page), 1))
set_page_dirty(page);
/*
@@ -1190,7 +1192,7 @@ void page_remove_rmap(struct page *page)
*/
if (unlikely(PageHuge(page)))
goto out;
- if (PageAnon(page)) {
+ if (anon) {
mem_cgroup_uncharge_page(page);
if (!PageTransHuge(page))
__dec_zone_page_state(page, NR_ANON_PAGES);
@@ -1211,7 +1213,8 @@ void page_remove_rmap(struct page *page)
* faster for those pages still in swapcache.
*/
out:
- mem_cgroup_end_update_page_stat(page, &locked, &flags);
+ if (!anon)
+ mem_cgroup_end_update_page_stat(page, &locked, &flags);
}
/*
--
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next prev parent reply other threads:[~2012-02-29 5:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-29 5:25 [PATCH 3.3] memcg: fix deadlock by inverting lrucare nesting Hugh Dickins
2012-02-29 5:26 ` Hugh Dickins [this message]
2012-02-29 19:35 ` [PATCH next] memcg: fix deadlock by avoiding stat lock when anon Johannes Weiner
2012-03-01 1:18 ` Hugh Dickins
2012-03-01 2:44 ` [PATCH v2 " Hugh Dickins
2012-03-01 9:18 ` KAMEZAWA Hiroyuki
2012-03-01 10:00 ` Johannes Weiner
2012-02-29 5:28 ` [PATCH next] memcg: remove PCG_FILE_MAPPED fix cosmetic fix Hugh Dickins
2012-02-29 5:40 ` KAMEZAWA Hiroyuki
2012-02-29 19:35 ` Johannes Weiner
2012-02-29 5:30 ` [PATCH next] memcg: remove PCG_CACHE page_cgroup flag fix Hugh Dickins
2012-02-29 5:54 ` KAMEZAWA Hiroyuki
2012-02-29 19:43 ` Johannes Weiner
2012-03-01 1:21 ` Hugh Dickins
2012-03-01 2:42 ` [PATCH next] memcg: remove PCG_CACHE page_cgroup flag fix2 Hugh Dickins
2012-03-01 9:16 ` KAMEZAWA Hiroyuki
2012-02-29 5:39 ` [PATCH 3.3] memcg: fix deadlock by inverting lrucare nesting KAMEZAWA Hiroyuki
2012-02-29 19:00 ` Johannes Weiner
2012-02-29 22:04 ` Andrew Morton
2012-03-01 0:43 ` Hugh Dickins
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