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Commit 297880f4 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size 



The page_counter rounds limits down to page size values.  This makes
sense, except in the case of hugetlb_cgroup where it's not possible to
charge partial hugepages.  If the hugetlb_cgroup margin is less than the
hugepage size being charged, it will fail as expected.

Round the hugetlb_cgroup limit down to hugepage size, since it is the
effective limit of the cgroup.

For consistency, round down PAGE_COUNTER_MAX as well when a
hugetlb_cgroup is created: this prevents error reports when a user
cannot restore the value to the kernel default.

Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nikolay Borisov <kernel@kyup.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 63678c32

mm/hugetlb_cgroup.c

+26 −9
Original line number Diff line number Diff line
@@ -67,26 +67,42 @@ static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg) 
	return false;

}



static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,

				struct hugetlb_cgroup *parent_h_cgroup)

{

	int idx;



	for (idx = 0; idx < HUGE_MAX_HSTATE; idx++) {

		struct page_counter *counter = &h_cgroup->hugepage[idx];

		struct page_counter *parent = NULL;

		unsigned long limit;

		int ret;



		if (parent_h_cgroup)

			parent = &parent_h_cgroup->hugepage[idx];

		page_counter_init(counter, parent);



		limit = round_down(PAGE_COUNTER_MAX,

				   1 << huge_page_order(&hstates[idx]));

		ret = page_counter_limit(counter, limit);

		VM_BUG_ON(ret);

	}

}



static struct cgroup_subsys_state *

hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)

{

	struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);

	struct hugetlb_cgroup *h_cgroup;

	int idx;



	h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);

	if (!h_cgroup)

		return ERR_PTR(-ENOMEM);



	if (parent_h_cgroup) {

		for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)

			page_counter_init(&h_cgroup->hugepage[idx],

					  &parent_h_cgroup->hugepage[idx]);

	} else {

	if (!parent_h_cgroup)

		root_h_cgroup = h_cgroup;

		for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)

			page_counter_init(&h_cgroup->hugepage[idx], NULL);

	}



	hugetlb_cgroup_init(h_cgroup, parent_h_cgroup);

	return &h_cgroup->css;

}
@@ -285,6 +301,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of, 
		return ret;



	idx = MEMFILE_IDX(of_cft(of)->private);

	nr_pages = round_down(nr_pages, 1 << huge_page_order(&hstates[idx]));



	switch (MEMFILE_ATTR(of_cft(of)->private)) {

	case RES_LIMIT: