mm: vmscan: do not scan anon pages if memcg swap limit is hit

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>

diff --git a/include/linux/swap.h b/include/linux/swap.h
index c2bd163a5e7e82c662e396d8f2a83c45b3020448..a587050204f9fbef4f4cb76854158dc9455cc7c4 100644 (file)
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -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__*/

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1ff552e3722b0eb8eafb609d40ad3a7cccd18311..bcb38718e174f1af77f362f584e049762ba552f7 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -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;

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9a8556e49cd922093bfe128284190c3fdfbf5ebc..3be5f9db6c422e5c1bca90290cd408b9d6b1c734 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -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;
        }