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

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 <>
Cc: Michal Hocko <>
Cc: Nikolay Borisov <>
Cc: Johannes Weiner <>
Cc: "Kirill A. Shutemov" <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 63678c32
......@@ -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);
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++)
} 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)) {
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