mm: vmscan: do not scan anon pages if memcg swap limit is hit
authorVladimir Davydov <vdavydov@virtuozzo.com>
Wed, 20 Jan 2016 23:03:07 +0000 (15:03 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 21 Jan 2016 01:09:18 +0000 (17:09 -0800)
We don't scan anonymous memory if we ran out of swap, neither should we do
it in case memcg swap limit is hit, because swap out is impossible anyway.

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>
include/linux/swap.h
mm/memcontrol.c
mm/vmscan.c

index c2bd163a5e7e82c662e396d8f2a83c45b3020448..a587050204f9fbef4f4cb76854158dc9455cc7c4 100644 (file)
@@ -551,6 +551,7 @@ static inline int mem_cgroup_swappiness(struct mem_cgroup *mem)
 extern void mem_cgroup_swapout(struct page *page, swp_entry_t entry);
 extern int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry);
 extern void mem_cgroup_uncharge_swap(swp_entry_t entry);
+extern long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg);
 #else
 static inline void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 {
@@ -565,6 +566,11 @@ static inline int mem_cgroup_try_charge_swap(struct page *page,
 static inline void mem_cgroup_uncharge_swap(swp_entry_t entry)
 {
 }
+
+static inline long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
+{
+       return get_nr_swap_pages();
+}
 #endif
 
 #endif /* __KERNEL__*/
index 1ff552e3722b0eb8eafb609d40ad3a7cccd18311..bcb38718e174f1af77f362f584e049762ba552f7 100644 (file)
@@ -5748,6 +5748,19 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry)
        rcu_read_unlock();
 }
 
+long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
+{
+       long nr_swap_pages = get_nr_swap_pages();
+
+       if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+               return nr_swap_pages;
+       for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
+               nr_swap_pages = min_t(long, nr_swap_pages,
+                                     READ_ONCE(memcg->swap.limit) -
+                                     page_counter_read(&memcg->swap));
+       return nr_swap_pages;
+}
+
 /* for remember boot option*/
 #ifdef CONFIG_MEMCG_SWAP_ENABLED
 static int really_do_swap_account __initdata = 1;
index 9a8556e49cd922093bfe128284190c3fdfbf5ebc..3be5f9db6c422e5c1bca90290cd408b9d6b1c734 100644 (file)
@@ -2004,7 +2004,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
                force_scan = true;
 
        /* If we have no swap space, do not bother scanning anon pages. */
-       if (!sc->may_swap || (get_nr_swap_pages() <= 0)) {
+       if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) {
                scan_balance = SCAN_FILE;
                goto out;
        }