diff options
author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2008-02-07 11:14:10 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-07 19:42:19 +0300 |
commit | ae41be374293e70e1ed441d986afcc6e744ef9d9 (patch) | |
tree | d8e2143820bbf3ed2f1f79ed99ee430284567b93 /mm/migrate.c | |
parent | 9175e0311ec9e6d1bf1f6dfecf9268baf08765e6 (diff) | |
download | linux-ae41be374293e70e1ed441d986afcc6e744ef9d9.tar.xz |
bugfix for memory cgroup controller: migration under memory controller fix
While using memory control cgroup, page-migration under it works as following.
==
1. uncharge all refs at try to unmap.
2. charge regs again remove_migration_ptes()
==
This is simple but has following problems.
==
The page is uncharged and charged back again if *mapped*.
- This means that cgroup before migration can be different from one after
migration
- If page is not mapped but charged as page cache, charge is just ignored
(because not mapped, it will not be uncharged before migration)
This is memory leak.
==
This patch tries to keep memory cgroup at page migration by increasing
one refcnt during it. 3 functions are added.
mem_cgroup_prepare_migration() --- increase refcnt of page->page_cgroup
mem_cgroup_end_migration() --- decrease refcnt of page->page_cgroup
mem_cgroup_page_migration() --- copy page->page_cgroup from old page to
new page.
During migration
- old page is under PG_locked.
- new page is under PG_locked, too.
- both old page and new page is not on LRU.
These 3 facts guarantee that page_cgroup() migration has no race.
Tested and worked well in x86_64/fake-NUMA box.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/migrate.c')
-rw-r--r-- | mm/migrate.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index 763794144697..a73504ff5ab9 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -593,9 +593,10 @@ static int move_to_new_page(struct page *newpage, struct page *page) else rc = fallback_migrate_page(mapping, newpage, page); - if (!rc) + if (!rc) { + mem_cgroup_page_migration(page, newpage); remove_migration_ptes(page, newpage); - else + } else newpage->mapping = NULL; unlock_page(newpage); @@ -614,6 +615,7 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, int *result = NULL; struct page *newpage = get_new_page(page, private, &result); int rcu_locked = 0; + int charge = 0; if (!newpage) return -ENOMEM; @@ -673,14 +675,19 @@ static int unmap_and_move(new_page_t get_new_page, unsigned long private, goto rcu_unlock; } + charge = mem_cgroup_prepare_migration(page); /* Establish migration ptes or remove ptes */ try_to_unmap(page, 1); if (!page_mapped(page)) rc = move_to_new_page(newpage, page); - if (rc) + if (rc) { remove_migration_ptes(page, page); + if (charge) + mem_cgroup_end_migration(page); + } else if (charge) + mem_cgroup_end_migration(newpage); rcu_unlock: if (rcu_locked) rcu_read_unlock(); |