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-rw-r--r--include/linux/memcontrol.h29
-rw-r--r--mm/vmscan.c27
2 files changed, 34 insertions, 22 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index bfe5c486f4ad..24797929d8a1 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -612,12 +612,15 @@ static inline bool mem_cgroup_disabled(void)
return !cgroup_subsys_enabled(memory_cgrp_subsys);
}
-static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root,
- struct mem_cgroup *memcg,
- bool in_low_reclaim)
+static inline void mem_cgroup_protection(struct mem_cgroup *root,
+ struct mem_cgroup *memcg,
+ unsigned long *min,
+ unsigned long *low)
{
+ *min = *low = 0;
+
if (mem_cgroup_disabled())
- return 0;
+ return;
/*
* There is no reclaim protection applied to a targeted reclaim.
@@ -653,13 +656,10 @@ static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root,
*
*/
if (root == memcg)
- return 0;
-
- if (in_low_reclaim)
- return READ_ONCE(memcg->memory.emin);
+ return;
- return max(READ_ONCE(memcg->memory.emin),
- READ_ONCE(memcg->memory.elow));
+ *min = READ_ONCE(memcg->memory.emin);
+ *low = READ_ONCE(memcg->memory.elow);
}
void mem_cgroup_calculate_protection(struct mem_cgroup *root,
@@ -1147,11 +1147,12 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm,
{
}
-static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root,
- struct mem_cgroup *memcg,
- bool in_low_reclaim)
+static inline void mem_cgroup_protection(struct mem_cgroup *root,
+ struct mem_cgroup *memcg,
+ unsigned long *min,
+ unsigned long *low)
{
- return 0;
+ *min = *low = 0;
}
static inline void mem_cgroup_calculate_protection(struct mem_cgroup *root,
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4620df62f0ff..b0202ab5e136 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -100,9 +100,12 @@ struct scan_control {
unsigned int may_swap:1;
/*
- * Cgroups are not reclaimed below their configured memory.low,
- * unless we threaten to OOM. If any cgroups are skipped due to
- * memory.low and nothing was reclaimed, go back for memory.low.
+ * Cgroup memory below memory.low is protected as long as we
+ * don't threaten to OOM. If any cgroup is reclaimed at
+ * reduced force or passed over entirely due to its memory.low
+ * setting (memcg_low_skipped), and nothing is reclaimed as a
+ * result, then go back for one more cycle that reclaims the protected
+ * memory (memcg_low_reclaim) to avert OOM.
*/
unsigned int memcg_low_reclaim:1;
unsigned int memcg_low_skipped:1;
@@ -2537,15 +2540,14 @@ out:
for_each_evictable_lru(lru) {
int file = is_file_lru(lru);
unsigned long lruvec_size;
+ unsigned long low, min;
unsigned long scan;
- unsigned long protection;
lruvec_size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
- protection = mem_cgroup_protection(sc->target_mem_cgroup,
- memcg,
- sc->memcg_low_reclaim);
+ mem_cgroup_protection(sc->target_mem_cgroup, memcg,
+ &min, &low);
- if (protection) {
+ if (min || low) {
/*
* Scale a cgroup's reclaim pressure by proportioning
* its current usage to its memory.low or memory.min
@@ -2576,6 +2578,15 @@ out:
* hard protection.
*/
unsigned long cgroup_size = mem_cgroup_size(memcg);
+ unsigned long protection;
+
+ /* memory.low scaling, make sure we retry before OOM */
+ if (!sc->memcg_low_reclaim && low > min) {
+ protection = low;
+ sc->memcg_low_skipped = 1;
+ } else {
+ protection = min;
+ }
/* Avoid TOCTOU with earlier protection check */
cgroup_size = max(cgroup_size, protection);