Merge tag 'renesas-fixes-for-v4.8' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e74d708..2ff0289 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4077,14 +4077,32 @@ static struct cftype mem_cgroup_legacy_files[] = {
 
 static DEFINE_IDR(mem_cgroup_idr);
 
-static void mem_cgroup_id_get(struct mem_cgroup *memcg)
+static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n)
 {
-       atomic_inc(&memcg->id.ref);
+       atomic_add(n, &memcg->id.ref);
 }
 
-static void mem_cgroup_id_put(struct mem_cgroup *memcg)
+static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
 {
-       if (atomic_dec_and_test(&memcg->id.ref)) {
+       while (!atomic_inc_not_zero(&memcg->id.ref)) {
+               /*
+                * The root cgroup cannot be destroyed, so it's refcount must
+                * always be >= 1.
+                */
+               if (WARN_ON_ONCE(memcg == root_mem_cgroup)) {
+                       VM_BUG_ON(1);
+                       break;
+               }
+               memcg = parent_mem_cgroup(memcg);
+               if (!memcg)
+                       memcg = root_mem_cgroup;
+       }
+       return memcg;
+}
+
+static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n)
+{
+       if (atomic_sub_and_test(n, &memcg->id.ref)) {
                idr_remove(&mem_cgroup_idr, memcg->id.id);
                memcg->id.id = 0;
 
@@ -4093,6 +4111,16 @@ static void mem_cgroup_id_put(struct mem_cgroup *memcg)
        }
 }
 
+static inline void mem_cgroup_id_get(struct mem_cgroup *memcg)
+{
+       mem_cgroup_id_get_many(memcg, 1);
+}
+
+static inline void mem_cgroup_id_put(struct mem_cgroup *memcg)
+{
+       mem_cgroup_id_put_many(memcg, 1);
+}
+
 /**
  * mem_cgroup_from_id - look up a memcg from a memcg id
  * @id: the memcg id to look up
@@ -4727,6 +4755,8 @@ static void __mem_cgroup_clear_mc(void)
                if (!mem_cgroup_is_root(mc.from))
                        page_counter_uncharge(&mc.from->memsw, mc.moved_swap);
 
+               mem_cgroup_id_put_many(mc.from, mc.moved_swap);
+
                /*
                 * we charged both to->memory and to->memsw, so we
                 * should uncharge to->memory.
@@ -4734,9 +4764,9 @@ static void __mem_cgroup_clear_mc(void)
                if (!mem_cgroup_is_root(mc.to))
                        page_counter_uncharge(&mc.to->memory, mc.moved_swap);
 
-               css_put_many(&mc.from->css, mc.moved_swap);
+               mem_cgroup_id_get_many(mc.to, mc.moved_swap);
+               css_put_many(&mc.to->css, mc.moved_swap);
 
-               /* we've already done css_get(mc.to) */
                mc.moved_swap = 0;
        }
        memcg_oom_recover(from);
@@ -5800,7 +5830,7 @@ subsys_initcall(mem_cgroup_init);
  */
 void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 {
-       struct mem_cgroup *memcg;
+       struct mem_cgroup *memcg, *swap_memcg;
        unsigned short oldid;
 
        VM_BUG_ON_PAGE(PageLRU(page), page);
@@ -5815,16 +5845,27 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
        if (!memcg)
                return;
 
-       mem_cgroup_id_get(memcg);
-       oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
+       /*
+        * In case the memcg owning these pages has been offlined and doesn't
+        * have an ID allocated to it anymore, charge the closest online
+        * ancestor for the swap instead and transfer the memory+swap charge.
+        */
+       swap_memcg = mem_cgroup_id_get_online(memcg);
+       oldid = swap_cgroup_record(entry, mem_cgroup_id(swap_memcg));
        VM_BUG_ON_PAGE(oldid, page);
-       mem_cgroup_swap_statistics(memcg, true);
+       mem_cgroup_swap_statistics(swap_memcg, true);
 
        page->mem_cgroup = NULL;
 
        if (!mem_cgroup_is_root(memcg))
                page_counter_uncharge(&memcg->memory, 1);
 
+       if (memcg != swap_memcg) {
+               if (!mem_cgroup_is_root(swap_memcg))
+                       page_counter_charge(&swap_memcg->memsw, 1);
+               page_counter_uncharge(&memcg->memsw, 1);
+       }
+
        /*
         * Interrupts should be disabled here because the caller holds the
         * mapping->tree_lock lock which is taken with interrupts-off. It is
@@ -5863,11 +5904,14 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry)
        if (!memcg)
                return 0;
 
+       memcg = mem_cgroup_id_get_online(memcg);
+
        if (!mem_cgroup_is_root(memcg) &&
-           !page_counter_try_charge(&memcg->swap, 1, &counter))
+           !page_counter_try_charge(&memcg->swap, 1, &counter)) {
+               mem_cgroup_id_put(memcg);
                return -ENOMEM;
+       }
 
-       mem_cgroup_id_get(memcg);
        oldid = swap_cgroup_record(entry, mem_cgroup_id(memcg));
        VM_BUG_ON_PAGE(oldid, page);
        mem_cgroup_swap_statistics(memcg, true);