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-rw-r--r--mm/memcontrol.c35
1 files changed, 28 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 50eb50e100fd..0e81eb5f0aea 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1111,6 +1111,23 @@ static bool mem_cgroup_check_under_limit(struct mem_cgroup *mem)
return false;
}
+/**
+ * mem_cgroup_check_margin - check if the memory cgroup allows charging
+ * @mem: memory cgroup to check
+ * @bytes: the number of bytes the caller intends to charge
+ *
+ * Returns a boolean value on whether @mem can be charged @bytes or
+ * whether this would exceed the limit.
+ */
+static bool mem_cgroup_check_margin(struct mem_cgroup *mem, unsigned long bytes)
+{
+ if (!res_counter_check_margin(&mem->res, bytes))
+ return false;
+ if (do_swap_account && !res_counter_check_margin(&mem->memsw, bytes))
+ return false;
+ return true;
+}
+
static unsigned int get_swappiness(struct mem_cgroup *memcg)
{
struct cgroup *cgrp = memcg->css.cgroup;
@@ -1852,15 +1869,19 @@ static int __mem_cgroup_do_charge(struct mem_cgroup *mem, gfp_t gfp_mask,
return CHARGE_WOULDBLOCK;
ret = mem_cgroup_hierarchical_reclaim(mem_over_limit, NULL,
- gfp_mask, flags);
+ gfp_mask, flags);
+ if (mem_cgroup_check_margin(mem_over_limit, csize))
+ return CHARGE_RETRY;
/*
- * try_to_free_mem_cgroup_pages() might not give us a full
- * picture of reclaim. Some pages are reclaimed and might be
- * moved to swap cache or just unmapped from the cgroup.
- * Check the limit again to see if the reclaim reduced the
- * current usage of the cgroup before giving up
+ * Even though the limit is exceeded at this point, reclaim
+ * may have been able to free some pages. Retry the charge
+ * before killing the task.
+ *
+ * Only for regular pages, though: huge pages are rather
+ * unlikely to succeed so close to the limit, and we fall back
+ * to regular pages anyway in case of failure.
*/
- if (ret || mem_cgroup_check_under_limit(mem_over_limit))
+ if (csize == PAGE_SIZE && ret)
return CHARGE_RETRY;
/*