From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: mm: memcontrol: move obj_cgroup_uncharge_pages() out of css_set_lock The css_set_lock is used to guard the list of inherited objcgs. So there is no need to uncharge kernel memory under css_set_lock. Just move it out of the lock. Link: https://lkml.kernel.org/r/20210417043538.9793-8-songmuchun@xxxxxxxxxxxxx Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Acked-by: Roman Gushchin <guro@xxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Cc: Xiongchun Duan <duanxiongchun@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/memcontrol.c~mm-memcontrol-move-obj_cgroup_uncharge_pages-out-of-css_set_lock +++ a/mm/memcontrol.c @@ -289,9 +289,10 @@ static void obj_cgroup_release(struct pe WARN_ON_ONCE(nr_bytes & (PAGE_SIZE - 1)); nr_pages = nr_bytes >> PAGE_SHIFT; - spin_lock_irqsave(&css_set_lock, flags); if (nr_pages) obj_cgroup_uncharge_pages(objcg, nr_pages); + + spin_lock_irqsave(&css_set_lock, flags); list_del(&objcg->list); spin_unlock_irqrestore(&css_set_lock, flags); _
