The patch titled
memcg: fix memory migration of shmem swapcache
has been added to the -mm tree. Its filename is
memcg-fix-memory-migration-of-shmem-swapcache.patch
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------------------------------------------------------
Subject: memcg: fix memory migration of shmem swapcache
From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
In the current implementation mem_cgroup_end_migration() decides whether
the page migration has succeeded or not by checking "oldpage->mapping".
But if we are tring to migrate a shmem swapcache, the page->mapping of it
is NULL from the begining, so the check would be invalid. As a result,
mem_cgroup_end_migration() assumes the migration has succeeded even if
it's not, so "newpage" would be freed while it's not uncharged.
This patch fixes it by passing mem_cgroup_end_migration() the result of
the page migration.
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 5 ++---
mm/memcontrol.c | 5 ++---
mm/migrate.c | 2 +-
3 files changed, 5 insertions(+), 7 deletions(-)
diff -puN include/linux/memcontrol.h~memcg-fix-memory-migration-of-shmem-swapcache include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~memcg-fix-memory-migration-of-shmem-swapcache
+++ a/include/linux/memcontrol.h
@@ -98,7 +98,7 @@ extern int
mem_cgroup_prepare_migration(struct page *page,
struct page *newpage, struct mem_cgroup **ptr);
extern void mem_cgroup_end_migration(struct mem_cgroup *mem,
- struct page *oldpage, struct page *newpage);
+ struct page *oldpage, struct page *newpage, bool migration_ok);
/*
* For memory reclaim.
@@ -251,8 +251,7 @@ mem_cgroup_prepare_migration(struct page
}
static inline void mem_cgroup_end_migration(struct mem_cgroup *mem,
- struct page *oldpage,
- struct page *newpage)
+ struct page *oldpage, struct page *newpage, bool migration_ok)
{
}
diff -puN mm/memcontrol.c~memcg-fix-memory-migration-of-shmem-swapcache mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-fix-memory-migration-of-shmem-swapcache
+++ a/mm/memcontrol.c
@@ -2896,7 +2896,7 @@ int mem_cgroup_prepare_migration(struct
/* remove redundant charge if migration failed*/
void mem_cgroup_end_migration(struct mem_cgroup *mem,
- struct page *oldpage, struct page *newpage)
+ struct page *oldpage, struct page *newpage, bool migration_ok)
{
struct page *used, *unused;
struct page_cgroup *pc;
@@ -2905,8 +2905,7 @@ void mem_cgroup_end_migration(struct mem
return;
/* blocks rmdir() */
cgroup_exclude_rmdir(&mem->css);
- /* at migration success, oldpage->mapping is NULL. */
- if (oldpage->mapping) {
+ if (!migration_ok) {
used = oldpage;
unused = newpage;
} else {
diff -puN mm/migrate.c~memcg-fix-memory-migration-of-shmem-swapcache mm/migrate.c
--- a/mm/migrate.c~memcg-fix-memory-migration-of-shmem-swapcache
+++ a/mm/migrate.c
@@ -761,7 +761,7 @@ rcu_unlock:
rcu_read_unlock();
uncharge:
if (!charge)
- mem_cgroup_end_migration(mem, page, newpage);
+ mem_cgroup_end_migration(mem, page, newpage, rc == 0);
unlock:
unlock_page(page);
_
Patches currently in -mm which might be from nishimura@xxxxxxxxxxxxxxxxx are
thp-transhuge-memcg-commit-tail-pages-at-charge.patch
thp-compound_trans_order-fix.patch
memcg-add-page_cgroup-flags-for-dirty-page-tracking.patch
memcg-document-cgroup-dirty-memory-interfaces.patch
memcg-document-cgroup-dirty-memory-interfaces-fix.patch
memcg-create-extensible-page-stat-update-routines.patch
memcg-add-lock-to-synchronize-page-accounting-and-migration.patch
memcg-fix-unit-mismatch-in-memcg-oom-limit-calculation.patch
memcg-fix-deadlock-between-cpuset-and-memcg.patch
memcg-fix-deadlock-between-cpuset-and-memcg-fix.patch
memcg-fix-memory-migration-of-shmem-swapcache.patch
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