diff options
-rw-r--r-- | mm/memcontrol.c | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 48354798e2a6..8f95896c5aa1 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5432,7 +5432,6 @@ static int mem_cgroup_move_account(struct page *page, { struct lruvec *from_vec, *to_vec; struct pglist_data *pgdat; - unsigned long flags; unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; int ret; bool anon; @@ -5459,18 +5458,13 @@ static int mem_cgroup_move_account(struct page *page, from_vec = mem_cgroup_lruvec(from, pgdat); to_vec = mem_cgroup_lruvec(to, pgdat); - spin_lock_irqsave(&from->move_lock, flags); + lock_page_memcg(page); if (!anon && page_mapped(page)) { __mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages); __mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages); } - /* - * move_lock grabbed above and caller set from->moving_account, so - * mod_memcg_page_state will serialize updates to PageDirty. - * So mapping should be stable for dirty pages. - */ if (!anon && PageDirty(page)) { struct address_space *mapping = page_mapping(page); @@ -5486,15 +5480,23 @@ static int mem_cgroup_move_account(struct page *page, } /* + * All state has been migrated, let's switch to the new memcg. + * * It is safe to change page->mem_cgroup here because the page - * is referenced, charged, and isolated - we can't race with - * uncharging, charging, migration, or LRU putback. + * is referenced, charged, isolated, and locked: we can't race + * with (un)charging, migration, LRU putback, or anything else + * that would rely on a stable page->mem_cgroup. + * + * Note that lock_page_memcg is a memcg lock, not a page lock, + * to save space. As soon as we switch page->mem_cgroup to a + * new memcg that isn't locked, the above state can change + * concurrently again. Make sure we're truly done with it. */ + smp_mb(); - /* caller should have done css_get */ - page->mem_cgroup = to; + page->mem_cgroup = to; /* caller should have done css_get */ - spin_unlock_irqrestore(&from->move_lock, flags); + __unlock_page_memcg(from); ret = 0; |