mm: memcontrol: take a css reference for each charged page
Charges currently pin the css indirectly by playing tricks during
css_offline(): user pages stall the offlining process until all of them
have been reparented, whereas kmemcg acquires a keep-alive reference if
outstanding kernel pages are detected at that point.
In preparation for removing all this complexity, make the pinning explicit
and acquire a css references for every charged page.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c3cd3bb..f69da2a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2273,6 +2273,7 @@
page_counter_uncharge(&old->memory, stock->nr_pages);
if (do_swap_account)
page_counter_uncharge(&old->memsw, stock->nr_pages);
+ css_put_many(&old->css, stock->nr_pages);
stock->nr_pages = 0;
}
stock->cached = NULL;
@@ -2530,6 +2531,7 @@
return -EINTR;
done_restock:
+ css_get_many(&memcg->css, batch);
if (batch > nr_pages)
refill_stock(memcg, batch - nr_pages);
done:
@@ -2544,6 +2546,8 @@
page_counter_uncharge(&memcg->memory, nr_pages);
if (do_swap_account)
page_counter_uncharge(&memcg->memsw, nr_pages);
+
+ css_put_many(&memcg->css, nr_pages);
}
/*
@@ -2739,6 +2743,7 @@
page_counter_charge(&memcg->memory, nr_pages);
if (do_swap_account)
page_counter_charge(&memcg->memsw, nr_pages);
+ css_get_many(&memcg->css, nr_pages);
ret = 0;
} else if (ret)
page_counter_uncharge(&memcg->kmem, nr_pages);
@@ -2754,8 +2759,10 @@
page_counter_uncharge(&memcg->memsw, nr_pages);
/* Not down to 0 */
- if (page_counter_uncharge(&memcg->kmem, nr_pages))
+ if (page_counter_uncharge(&memcg->kmem, nr_pages)) {
+ css_put_many(&memcg->css, nr_pages);
return;
+ }
/*
* Releases a reference taken in kmem_cgroup_css_offline in case
@@ -2767,6 +2774,8 @@
*/
if (memcg_kmem_test_and_clear_dead(memcg))
css_put(&memcg->css);
+
+ css_put_many(&memcg->css, nr_pages);
}
/*
@@ -3394,10 +3403,13 @@
ret = mem_cgroup_move_account(page, nr_pages,
pc, child, parent);
if (!ret) {
+ if (!mem_cgroup_is_root(parent))
+ css_get_many(&parent->css, nr_pages);
/* Take charge off the local counters */
page_counter_cancel(&child->memory, nr_pages);
if (do_swap_account)
page_counter_cancel(&child->memsw, nr_pages);
+ css_put_many(&child->css, nr_pages);
}
if (nr_pages > 1)
@@ -5767,7 +5779,6 @@
{
struct mem_cgroup *from = mc.from;
struct mem_cgroup *to = mc.to;
- int i;
/* we must uncharge all the leftover precharges from mc.to */
if (mc.precharge) {
@@ -5795,8 +5806,7 @@
if (!mem_cgroup_is_root(mc.to))
page_counter_uncharge(&mc.to->memory, mc.moved_swap);
- for (i = 0; i < mc.moved_swap; i++)
- css_put(&mc.from->css);
+ css_put_many(&mc.from->css, mc.moved_swap);
/* we've already done css_get(mc.to) */
mc.moved_swap = 0;
@@ -6343,6 +6353,9 @@
__this_cpu_add(memcg->stat->nr_page_events, nr_anon + nr_file);
memcg_check_events(memcg, dummy_page);
local_irq_restore(flags);
+
+ if (!mem_cgroup_is_root(memcg))
+ css_put_many(&memcg->css, max(nr_mem, nr_memsw));
}
static void uncharge_list(struct list_head *page_list)