diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index 2ad6e92f124adc121a7692ec66ebaedea0d2c4ca..0bff345c4bc68460381aa7af563f02b61cc7e998 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -113,6 +113,11 @@ static inline bool hugetlb_cgroup_disabled(void)
return !cgroup_subsys_enabled(hugetlb_cgrp_subsys);
}
+static inline void hugetlb_cgroup_put_rsvd_cgroup(struct hugetlb_cgroup *h_cg)
+{
+ css_put(&h_cg->css);
+}
+
extern int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
struct hugetlb_cgroup **ptr);
extern int hugetlb_cgroup_charge_cgroup_rsvd(int idx, unsigned long nr_pages,
@@ -138,7 +143,8 @@ extern void hugetlb_cgroup_uncharge_counter(struct resv_map *resv,
extern void hugetlb_cgroup_uncharge_file_region(struct resv_map *resv,
struct file_region *rg,
- unsigned long nr_pages);
+ unsigned long nr_pages,
+ bool region_del);
extern void hugetlb_cgroup_file_init(void) __init;
extern void hugetlb_cgroup_migrate(struct page *oldhpage,
@@ -147,7 +153,8 @@ extern void hugetlb_cgroup_migrate(struct page *oldhpage,
#else
static inline void hugetlb_cgroup_uncharge_file_region(struct resv_map *resv,
struct file_region *rg,
- unsigned long nr_pages)
+ unsigned long nr_pages,
+ bool region_del)
{
}
@@ -185,6 +192,10 @@ static inline bool hugetlb_cgroup_disabled(void)
return true;
}
+static inline void hugetlb_cgroup_put_rsvd_cgroup(struct hugetlb_cgroup *h_cg)
+{
+}
+
static inline int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
struct hugetlb_cgroup **ptr)
{
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 5b1ab1f427c57cd1a66c29d9fca147d02bf229d4..a86a58ef132d55690e92025039aa5024dce141b3 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -280,6 +280,17 @@ static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg,
nrg->reservation_counter =
&h_cg->rsvd_hugepage[hstate_index(h)];
nrg->css = &h_cg->css;
+ /*
+ * The caller will hold exactly one h_cg->css reference for the
+ * whole contiguous reservation region. But this area might be
+ * scattered when there are already some file_regions reside in
+ * it. As a result, many file_regions may share only one css
+ * reference. In order to ensure that one file_region must hold
+ * exactly one h_cg->css reference, we should do css_get for
+ * each file_region and leave the reference held by caller
+ * untouched.
+ */
+ css_get(&h_cg->css);
if (!resv->pages_per_hpage)
resv->pages_per_hpage = pages_per_huge_page(h);
/* pages_per_hpage should be the same for all entries in
@@ -293,6 +304,14 @@ static void record_hugetlb_cgroup_uncharge_info(struct hugetlb_cgroup *h_cg,
#endif
}
+static void put_uncharge_info(struct file_region *rg)
+{
+#ifdef CONFIG_CGROUP_HUGETLB
+ if (rg->css)
+ css_put(rg->css);
+#endif
+}
+
static bool has_same_uncharge_info(struct file_region *rg,
struct file_region *org)
{
@@ -316,6 +335,7 @@ static void coalesce_file_region(struct resv_map *resv, struct file_region *rg)
prg->to = rg->to;
list_del(&rg->link);
+ put_uncharge_info(rg);
kfree(rg);
rg = prg;
@@ -327,6 +347,7 @@ static void coalesce_file_region(struct resv_map *resv, struct file_region *rg)
nrg->from = rg->from;
list_del(&rg->link);
+ put_uncharge_info(rg);
kfree(rg);
}
}
@@ -662,7 +683,7 @@ retry:
del += t - f;
hugetlb_cgroup_uncharge_file_region(
- resv, rg, t - f);
+ resv, rg, t - f, false);
/* New entry for end of split region */
nrg->from = t;
@@ -683,7 +704,7 @@ retry:
if (f <= rg->from && t >= rg->to) { /* Remove entire region */
del += rg->to - rg->from;
hugetlb_cgroup_uncharge_file_region(resv, rg,
- rg->to - rg->from);
+ rg->to - rg->from, true);
list_del(&rg->link);
kfree(rg);
continue;
@@ -691,13 +712,13 @@ retry:
if (f <= rg->from) { /* Trim beginning of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
- t - rg->from);
+ t - rg->from, false);
del += t - rg->from;
rg->from = t;
} else { /* Trim end of region */
hugetlb_cgroup_uncharge_file_region(resv, rg,
- rg->to - f);
+ rg->to - f, false);
del += rg->to - f;
rg->to = f;
@@ -5187,6 +5208,10 @@ bool hugetlb_reserve_pages(struct inode *inode,
*/
long rsv_adjust;
+ /*
+ * hugetlb_cgroup_uncharge_cgroup_rsvd() will put the
+ * reference to h_cg->css. See comment below for detail.
+ */
hugetlb_cgroup_uncharge_cgroup_rsvd(
hstate_index(h),
(chg - add) * pages_per_huge_page(h), h_cg);
@@ -5194,6 +5219,14 @@ bool hugetlb_reserve_pages(struct inode *inode,
rsv_adjust = hugepage_subpool_put_pages(spool,
chg - add);
hugetlb_acct_memory(h, -rsv_adjust);
+ } else if (h_cg) {
+ /*
+ * The file_regions will hold their own reference to
+ * h_cg->css. So we should release the reference held
+ * via hugetlb_cgroup_charge_cgroup_rsvd() when we are
+ * done.
+ */
+ hugetlb_cgroup_put_rsvd_cgroup(h_cg);
}
}
return true;
diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index f68b51fcda3d137d9904206922ac4dbc100adce8..603a131e262dc75ca4cb61f87e6751ef8368de4b 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -391,7 +391,8 @@ void hugetlb_cgroup_uncharge_counter(struct resv_map *resv, unsigned long start,
void hugetlb_cgroup_uncharge_file_region(struct resv_map *resv,
struct file_region *rg,
- unsigned long nr_pages)
+ unsigned long nr_pages,
+ bool region_del)
{
if (hugetlb_cgroup_disabled() || !resv || !rg || !nr_pages)
return;
@@ -400,7 +401,12 @@ void hugetlb_cgroup_uncharge_file_region(struct resv_map *resv,
!resv->reservation_counter) {
page_counter_uncharge(rg->reservation_counter,
nr_pages * resv->pages_per_hpage);
- css_put(rg->css);
+ /*
+ * Only do css_put(rg->css) when we delete the entire region
+ * because one file_region must hold exactly one css reference.
+ */
+ if (region_del)
+ css_put(rg->css);
}
}