Commit 62b3bd2a authored by Johannes Weiner's avatar Johannes Weiner Committed by Sasha Levin

mm: memcontrol: reclaim when shrinking memory.high below usage

[ Upstream commit 588083bb ]

When setting memory.high below usage, nothing happens until the next
charge comes along, and then it will only reclaim its own charge and not
the now potentially huge excess of the new memory.high.  This can cause
groups to stay in excess of their memory.high indefinitely.

To fix that, when shrinking memory.high, kick off a reclaim cycle that
goes after the delta.
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
parent 15207f3c
......@@ -5289,6 +5289,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of));
unsigned long nr_pages;
unsigned long high;
int err;
......@@ -5299,6 +5300,11 @@ static ssize_t memory_high_write(struct kernfs_open_file *of,
memcg->high = high;
nr_pages = page_counter_read(&memcg->memory);
if (nr_pages > high)
try_to_free_mem_cgroup_pages(memcg, nr_pages - high,
GFP_KERNEL, true);
return nbytes;
}
......
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