vmscan,memcg: memcg aware swap token

Currently, memcg reclaim can disable swap token even if the swap token mm
doesn't belong in its memory cgroup.  It's slightly risky.  If an admin
creates very small mem-cgroup and silly guy runs contentious heavy memory
pressure workload, every tasks are going to lose swap token and then
system may become unresponsive.  That's bad.

This patch adds 'memcg' parameter into disable_swap_token().  and if the
parameter doesn't match swap token, VM doesn't disable it.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Rik van Riel<riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 6 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 384eb5fe530b..e70564647039 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -358,6 +358,7 @@ struct backing_dev_info;
 extern struct mm_struct *swap_token_mm;
 extern void grab_swap_token(struct mm_struct *);
 extern void __put_swap_token(struct mm_struct *);
+extern void disable_swap_token(struct mem_cgroup *memcg);
 
 static inline int has_swap_token(struct mm_struct *mm)
 {
@@ -370,11 +371,6 @@ static inline void put_swap_token(struct mm_struct *mm)
                 __put_swap_token(mm);
 }
 
-static inline void disable_swap_token(void)
-{
-        put_swap_token(swap_token_mm);
-}
-
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 extern void
 mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout);
@@ -500,7 +496,7 @@ static inline int has_swap_token(struct mm_struct *mm)
         return 0;
 }
 
-static inline void disable_swap_token(void)
+static inline void disable_swap_token(struct mem_cgroup *memcg)
 {
 }