Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

Minor overlapping changes for both merge conflicts.

Resolution work done by Stephen Rothwell was used
as a reference.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 68 insertions, 14 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 66beca1ad92f..2ff0289ad061 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2337,8 +2337,11 @@ int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
 		return 0;
 
 	memcg = get_mem_cgroup_from_mm(current->mm);
-	if (!mem_cgroup_is_root(memcg))
+	if (!mem_cgroup_is_root(memcg)) {
 		ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
+		if (!ret)
+			__SetPageKmemcg(page);
+	}
 	css_put(&memcg->css);
 	return ret;
 }
@@ -2365,6 +2368,11 @@ void memcg_kmem_uncharge(struct page *page, int order)
 		page_counter_uncharge(&memcg->memsw, nr_pages);
 
 	page->mem_cgroup = NULL;
+
+	/* slab pages do not have PageKmemcg flag set */
+	if (PageKmemcg(page))
+		__ClearPageKmemcg(page);
+
 	css_put_many(&memcg->css, nr_pages);
 }
 #endif /* !CONFIG_SLOB */
@@ -4069,14 +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;
 
@@ -4085,6 +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
@@ -4719,6 +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.
@@ -4726,9 +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);
@@ -5537,8 +5575,10 @@ static void uncharge_list(struct list_head *page_list)
 			else
 				nr_file += nr_pages;
 			pgpgout++;
-		} else
+		} else {
 			nr_kmem += 1 << compound_order(page);
+			__ClearPageKmemcg(page);
+		}
 
 		page->mem_cgroup = NULL;
 	} while (next != page_list);
@@ -5790,7 +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);
@@ -5805,16 +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
@@ -5853,11 +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);