On Tue, Oct 27, 2020 at 04:02:55PM +0800, Muchun Song wrote:
> 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.
>
> Fixes: ec9f02384f60 ("mm: workingset: fix vmstat counters for shadow nodes")
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Can you, please, drop this patch for now?
I'm working on a bigger cleanup related to the handling of the root memory
cgroup (I sent a link earlier in this thread), which already does a similar change.
There are several issues like this one, so it will be nice to fix them all at once.
Thank you!
> ---
> mm/memcontrol.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 22b4fb941b54..70345b15b150 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -875,8 +875,13 @@ void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)
> rcu_read_lock();
> memcg = mem_cgroup_from_obj(p);
>
> - /* 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(memcg, pgdat);
> --
> 2.20.1
>
