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

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: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Johannes Weiner 2016-03-17 14:20:25 -07:00 committed by Linus Torvalds
parent d9b2ddf807
commit 588083bb37
1 changed files with 6 additions and 0 deletions
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6
mm/memcontrol.c
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@ -4992,6 +4992,7 @@ 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;
@ -5002,6 +5003,11 @@ 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);
memcg_wb_domain_size_changed(memcg);
return nbytes;
}