Commit 588083bb authored Mar 17, 2016 by Johannes Weiner Committed by Linus Torvalds Mar 17, 2016

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>

parent d9b2ddf8

mm/memcontrol.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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;
		}

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