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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2008-02-07 00:14:10 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-07 08:42:19 -0800
commitae41be374293e70e1ed441d986afcc6e744ef9d9 (patch)
treed8e2143820bbf3ed2f1f79ed99ee430284567b93 /include/linux/memcontrol.h
parent9175e0311ec9e6d1bf1f6dfecf9268baf08765e6 (diff)
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 'include/linux/memcontrol.h')
-rw-r--r--include/linux/memcontrol.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 42536c737d9..4ec712967f7 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -60,6 +60,10 @@ static inline void mem_cgroup_uncharge_page(struct page *page)
mem_cgroup_uncharge(page_get_page_cgroup(page));
}
+extern int mem_cgroup_prepare_migration(struct page *page);
+extern void mem_cgroup_end_migration(struct page *page);
+extern void mem_cgroup_page_migration(struct page *page, struct page *newpage);
+
#else /* CONFIG_CGROUP_MEM_CONT */
static inline void mm_init_cgroup(struct mm_struct *mm,
struct task_struct *p)
@@ -117,6 +121,21 @@ static inline int task_in_mem_cgroup(struct task_struct *task,
return 1;
}
+static inline int mem_cgroup_prepare_migration(struct page *page)
+{
+ return 0;
+}
+
+static inline void mem_cgroup_end_migration(struct page *page)
+{
+}
+
+static inline void
+mem_cgroup_page_migration(struct page *page, struct page *newpage)
+{
+}
+
+
#endif /* CONFIG_CGROUP_MEM_CONT */
#endif /* _LINUX_MEMCONTROL_H */