mm: fix memcg stack accounting for sub-page stacks

[mirror_ubuntu-bionic-kernel.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index af3637e0ee52dbd71e0a9075fbd5aaf47304f1f3..52e725d4a866b4ac30f16b4db075b9b197e4e53d 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -165,20 +165,12 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
        struct page *page = alloc_pages_node(node, THREADINFO_GFP,
                                             THREAD_SIZE_ORDER);
 
-       if (page)
-               memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK,
-                                           1 << THREAD_SIZE_ORDER);
-
        return page ? page_address(page) : NULL;
 }
 
 static inline void free_thread_stack(unsigned long *stack)
 {
-       struct page *page = virt_to_page(stack);
-
-       memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK,
-                                   -(1 << THREAD_SIZE_ORDER));
-       __free_pages(page, THREAD_SIZE_ORDER);
+       __free_pages(virt_to_page(stack), THREAD_SIZE_ORDER);
 }
 # else
 static struct kmem_cache *thread_stack_cache;
@@ -223,10 +215,15 @@ static struct kmem_cache *mm_cachep;
 
 static void account_kernel_stack(unsigned long *stack, int account)
 {
-       struct zone *zone = page_zone(virt_to_page(stack));
+       /* All stack pages are in the same zone and belong to the same memcg. */
+       struct page *first_page = virt_to_page(stack);
 
-       mod_zone_page_state(zone, NR_KERNEL_STACK_KB,
+       mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
                            THREAD_SIZE / 1024 * account);
+
+       memcg_kmem_update_page_stat(
+               first_page, MEMCG_KERNEL_STACK_KB,
+               account * (THREAD_SIZE / 1024));
 }
 
 void free_task(struct task_struct *tsk)