This is a note to let you know that I've just added the patch titled mm: memcg/slab: fix root memcg vmstats to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mm-memcg-slab-fix-root-memcg-vmstats.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 8faeb1ffd79593c9cd8a2a80ecdda371e3b826cb Mon Sep 17 00:00:00 2001 From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Date: Sat, 21 Nov 2020 22:17:12 -0800 Subject: mm: memcg/slab: fix root memcg vmstats From: Muchun Song <songmuchun@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Christopher Lameter <cl@xxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Yafang Shao <laoar.shao@xxxxxxxxx> Cc: Chris Down <chris@xxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [5.3+] Link: https://lkml.kernel.org/r/20201110031015.15715-1-songmuchun@xxxxxxxxxxxxx Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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); Patches currently in stable-queue which might be from songmuchun@xxxxxxxxxxxxx are queue-5.4/mm-memcg-slab-fix-root-memcg-vmstats.patch