Introduce swap_cgroup_init()/swap_cgroup_free() to allocate buffers when creating the first
non-root memcg and deallocate buffers on the last non-root memcg is gone.
Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
CC: Glauber Costa <glommer@xxxxxxxxxxxxx>
CC: Michal Hocko <mhocko@xxxxxxx>
CC: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
CC: Johannes Weiner <hannes@xxxxxxxxxxx>
CC: Mel Gorman <mgorman@xxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: Sha Zhengju <handai.szj@xxxxxxxxxx>
---
include/linux/page_cgroup.h | 12 +++++
mm/page_cgroup.c | 108 +++++++++++++++++++++++++++++++++++++++----
2 files changed, 110 insertions(+), 10 deletions(-)
diff --git a/include/linux/page_cgroup.h b/include/linux/page_cgroup.h
index 777a524..1255cc9 100644
--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -113,6 +113,8 @@ extern unsigned short swap_cgroup_record(swp_entry_t ent, unsigned short id);
extern unsigned short lookup_swap_cgroup_id(swp_entry_t ent);
extern int swap_cgroup_swapon(int type, unsigned long max_pages);
extern void swap_cgroup_swapoff(int type);
+extern int swap_cgroup_init(void);
+extern void swap_cgroup_free(void);
#else
static inline
@@ -138,6 +140,16 @@ static inline void swap_cgroup_swapoff(int type)
return;
}
+static inline int swap_cgroup_init(void)
+{
+ return 0;
+}
+
+static inline void swap_cgroup_free(void)
+{
+ return;
+}
+
#endif /* CONFIG_MEMCG_SWAP */
#endif /* !__GENERATING_BOUNDS_H */
diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c
index 189fbf5..0ebd127 100644
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -362,14 +362,28 @@ static int swap_cgroup_prepare(int type)
unsigned long idx, max;
ctrl = &swap_cgroup_ctrl[type];
+ if (!ctrl->length) {
+ /*
+ * Bypass the buffer allocation if the corresponding swap
+ * partition/file was turned off.
+ */
+ pr_debug("couldn't allocate swap_cgroup on a disabled swap "
+ "partition or file, index: %d\n", type);
+ return 0;
+ }
+
ctrl->map = vzalloc(ctrl->length * sizeof(void *));
- if (!ctrl->map)
+ if (!ctrl->map) {
+ ctrl->length = 0;
goto nomem;
+ }
for (idx = 0; idx < ctrl->length; idx++) {
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
- if (!page)
+ if (!page) {
+ ctrl->length = 0;
goto not_enough_page;
+ }
ctrl->map[idx] = page;
}
return 0;
@@ -383,6 +397,32 @@ nomem:
return -ENOMEM;
}
+/*
+ * free buffer for swap_cgroup.
+ */
+static void swap_cgroup_teardown(int type)
+{
+ struct page **map;
+ unsigned long length;
+ struct swap_cgroup_ctrl *ctrl;
+
+ ctrl = &swap_cgroup_ctrl[type];
+ map = ctrl->map;
+ length = ctrl->length;
+ ctrl->map = NULL;
+ ctrl->length = 0;
+
+ if (map) {
+ unsigned long i;
+ for (i = 0; i < length; i++) {
+ struct page *page = map[i];
+ if (page)
+ __free_page(page);
+ }
+ vfree(map);
+ }
+}
+
static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
struct swap_cgroup_ctrl **ctrlp)
{
@@ -474,6 +514,56 @@ unsigned short lookup_swap_cgroup_id(swp_entry_t ent)
return sc ? sc->id : 0;
}
+/*
+ * Allocate swap cgroup accounting structures when the first non-root
+ * memcg is created.
+ */
+int swap_cgroup_init(void)
+{
+ unsigned int type;
+
+ if (!do_swap_account)
+ return 0;
+
+ if (atomic_add_return(1, &memsw_accounting_users) != 1)
+ return 0;
+
+ mutex_lock(&swap_cgroup_mutex);
+ for (type = 0; type < nr_swapfiles; type++) {
+ if (swap_cgroup_prepare(type) < 0) {
+ mutex_unlock(&swap_cgroup_mutex);
+ goto nomem;
+ }
+ }
+ mutex_unlock(&swap_cgroup_mutex);
+ return 0;
+
+nomem:
+ pr_info("couldn't allocate enough memory for swap_cgroup "
+ "while creating non-root memcg.\n");
+ return -ENOMEM;
+}
+
+/*
+ * Deallocate swap cgroup accounting structures on the last non-root
+ * memcg removal.
+ */
+void swap_cgroup_free(void)
+{
+ unsigned int type;
+
+ if (!do_swap_account)
+ return;
+
+ if (atomic_sub_return(1, &memsw_accounting_users))
+ return;
+
+ mutex_lock(&swap_cgroup_mutex);
+ for (type = 0; type < nr_swapfiles; type++)
+ swap_cgroup_teardown(type);
+ mutex_unlock(&swap_cgroup_mutex);
+}
+
int swap_cgroup_swapon(int type, unsigned long max_pages)
{
unsigned long length;
@@ -482,20 +572,18 @@ int swap_cgroup_swapon(int type, unsigned long max_pages)
if (!do_swap_account)
return 0;
- if (!atomic_read(&memsw_accounting_users))
- return 0;
-
length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
ctrl = &swap_cgroup_ctrl[type];
mutex_lock(&swap_cgroup_mutex);
ctrl->length = length;
spin_lock_init(&ctrl->lock);
- if (swap_cgroup_prepare(type)) {
- /* memory shortage */
- ctrl->length = 0;
- mutex_unlock(&swap_cgroup_mutex);
- goto nomem;
+ if (atomic_read(&memsw_accounting_users)) {
+ if (swap_cgroup_prepare(type)) {
+ /* memory shortage */
+ mutex_unlock(&swap_cgroup_mutex);
+ goto nomem;
+ }
}
mutex_unlock(&swap_cgroup_mutex);
--
1.7.9.5
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