mm: free swap cache aggressively if memcg swap is full

Swap cache pages are freed aggressively if swap is nearly full (>50%
currently), because otherwise we are likely to stop scanning anonymous
when we near the swap limit even if there is plenty of freeable swap cache
pages.  We should follow the same trend in case of memory cgroup, which
has its own swap limit.

Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/memory.c b/mm/memory.c
index ff17850a52d9..30991f83d0bf 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2582,7 +2582,8 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
         }
 
         swap_free(entry);
-        if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
+        if (mem_cgroup_swap_full(page) ||
+            (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
                 try_to_free_swap(page);
         unlock_page(page);
         if (page != swapcache) {