lkml.org 
[lkml]   [2020]   [Nov]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.4 155/158] mm: memcg/slab: fix root memcg vmstats
Date
From: Muchun Song <songmuchun@bytedance.com>

commit 8faeb1ffd79593c9cd8a2a80ecdda371e3b826cb upstream.

If we reparent the slab objects to the root memcg, when we free the slab
object, we need to update the per-memcg vmstats to keep it correct for
the root memcg. Now this at least affects the vmstat of
NR_KERNEL_STACK_KB for !CONFIG_VMAP_STACK when the thread stack size is
smaller than the PAGE_SIZE.

David said:
"I assume that without this fix that the root memcg's vmstat would
always be inflated if we reparented"

Fixes: ec9f02384f60 ("mm: workingset: fix vmstat counters for shadow nodes")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Chris Down <chris@chrisdown.name>
Cc: <stable@vger.kernel.org> [5.3+]
Link: https://lkml.kernel.org/r/20201110031015.15715-1-songmuchun@bytedance.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
mm/memcontrol.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -776,8 +776,13 @@ void __mod_lruvec_slab_state(void *p, en
rcu_read_lock();
memcg = memcg_from_slab_page(page);

- /* Untracked pages have no memcg, no lruvec. Update only the node */
- if (!memcg || memcg == root_mem_cgroup) {
+ /*
+ * Untracked pages have no memcg, no lruvec. Update only the
+ * node. If we reparent the slab objects to the root memcg,
+ * when we free the slab object, we need to update the per-memcg
+ * vmstats to keep it correct for the root memcg.
+ */
+ if (!memcg) {
__mod_node_page_state(pgdat, idx, val);
} else {
lruvec = mem_cgroup_lruvec(pgdat, memcg);

\
 
 \ /
  Last update: 2020-11-23 14:40    [W:0.767 / U:0.540 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site