mm: memcontrol: remove unnecessary PCG_MEMSW memory+swap charge flag

Now that mem_cgroup_swapout() fully uncharges the page, every page that is
still in use when reaching mem_cgroup_uncharge() is known to carry both
the memory and the memory+swap charge.  Simplify the uncharge path and
remove the PCG_MEMSW page flag accordingly.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 5c831f1eca798d06e35c02c32e29353cc511d74e..da62ee2be28b56d35b1a20ba46f510b74d460a85 100644 (file)
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -5,7 +5,6 @@ enum {
        /* flags for mem_cgroup */
        PCG_USED = 0x01,        /* This page is charged to a memcg */
        PCG_MEM = 0x02,         /* This page holds a memory charge */
-       PCG_MEMSW = 0x04,       /* This page holds a memory+swap charge */
 };
 
 struct pglist_data;

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 266a440c89f9d6c01fc40fc6648efa2af432d44f..baf3b535b180d63d4d7d76be79387497f18b7320 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2614,7 +2614,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
         *   have the page locked
         */
        pc->mem_cgroup = memcg;
-       pc->flags = PCG_USED | PCG_MEM | (do_swap_account ? PCG_MEMSW : 0);
+       pc->flags = PCG_USED | PCG_MEM;
 
        if (lrucare)
                unlock_page_lru(page, isolated);
@@ -5793,7 +5793,6 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
        if (!PageCgroupUsed(pc))
                return;
 
-       VM_BUG_ON_PAGE(!(pc->flags & PCG_MEMSW), page);
        memcg = pc->mem_cgroup;
 
        oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
@@ -5989,17 +5988,16 @@ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg)
 }
 
 static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
-                          unsigned long nr_mem, unsigned long nr_memsw,
                           unsigned long nr_anon, unsigned long nr_file,
                           unsigned long nr_huge, struct page *dummy_page)
 {
+       unsigned long nr_pages = nr_anon + nr_file;
        unsigned long flags;
 
        if (!mem_cgroup_is_root(memcg)) {
-               if (nr_mem)
-                       page_counter_uncharge(&memcg->memory, nr_mem);
-               if (nr_memsw)
-                       page_counter_uncharge(&memcg->memsw, nr_memsw);
+               page_counter_uncharge(&memcg->memory, nr_pages);
+               if (do_swap_account)
+                       page_counter_uncharge(&memcg->memsw, nr_pages);
                memcg_oom_recover(memcg);
        }
 
@@ -6008,23 +6006,21 @@ static void uncharge_batch(struct mem_cgroup *memcg, unsigned long pgpgout,
        __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_CACHE], nr_file);
        __this_cpu_sub(memcg->stat->count[MEM_CGROUP_STAT_RSS_HUGE], nr_huge);
        __this_cpu_add(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT], pgpgout);
-       __this_cpu_add(memcg->stat->nr_page_events, nr_anon + nr_file);
+       __this_cpu_add(memcg->stat->nr_page_events, nr_pages);
        memcg_check_events(memcg, dummy_page);
        local_irq_restore(flags);
 
        if (!mem_cgroup_is_root(memcg))
-               css_put_many(&memcg->css, max(nr_mem, nr_memsw));
+               css_put_many(&memcg->css, nr_pages);
 }
 
 static void uncharge_list(struct list_head *page_list)
 {
        struct mem_cgroup *memcg = NULL;
-       unsigned long nr_memsw = 0;
        unsigned long nr_anon = 0;
        unsigned long nr_file = 0;
        unsigned long nr_huge = 0;
        unsigned long pgpgout = 0;
-       unsigned long nr_mem = 0;
        struct list_head *next;
        struct page *page;
 
@@ -6051,10 +6047,9 @@ static void uncharge_list(struct list_head *page_list)
 
                if (memcg != pc->mem_cgroup) {
                        if (memcg) {
-                               uncharge_batch(memcg, pgpgout, nr_mem, nr_memsw,
-                                              nr_anon, nr_file, nr_huge, page);
-                               pgpgout = nr_mem = nr_memsw = 0;
-                               nr_anon = nr_file = nr_huge = 0;
+                               uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
+                                              nr_huge, page);
+                               pgpgout = nr_anon = nr_file = nr_huge = 0;
                        }
                        memcg = pc->mem_cgroup;
                }
@@ -6070,18 +6065,14 @@ static void uncharge_list(struct list_head *page_list)
                else
                        nr_file += nr_pages;
 
-               if (pc->flags & PCG_MEM)
-                       nr_mem += nr_pages;
-               if (pc->flags & PCG_MEMSW)
-                       nr_memsw += nr_pages;
                pc->flags = 0;
 
                pgpgout++;
        } while (next != page_list);
 
        if (memcg)
-               uncharge_batch(memcg, pgpgout, nr_mem, nr_memsw,
-                              nr_anon, nr_file, nr_huge, page);
+               uncharge_batch(memcg, pgpgout, nr_anon, nr_file,
+                              nr_huge, page);
 }
 
 /**
@@ -6166,7 +6157,6 @@ void mem_cgroup_migrate(struct page *oldpage, struct page *newpage,
                return;
 
        VM_BUG_ON_PAGE(!(pc->flags & PCG_MEM), oldpage);
-       VM_BUG_ON_PAGE(do_swap_account && !(pc->flags & PCG_MEMSW), oldpage);
 
        if (lrucare)
                lock_page_lru(oldpage, &isolated);