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-rw-r--r--mm/page_alloc.c51
1 files changed, 38 insertions, 13 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ceb45a8e1359..019af778ec55 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3677,6 +3677,39 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
return false;
}
+static inline bool
+check_retry_cpuset(int cpuset_mems_cookie, struct alloc_context *ac)
+{
+ /*
+ * It's possible that cpuset's mems_allowed and the nodemask from
+ * mempolicy don't intersect. This should be normally dealt with by
+ * policy_nodemask(), but it's possible to race with cpuset update in
+ * such a way the check therein was true, and then it became false
+ * before we got our cpuset_mems_cookie here.
+ * This assumes that for all allocations, ac->nodemask can come only
+ * from MPOL_BIND mempolicy (whose documented semantics is to be ignored
+ * when it does not intersect with the cpuset restrictions) or the
+ * caller can deal with a violated nodemask.
+ */
+ if (cpusets_enabled() && ac->nodemask &&
+ !cpuset_nodemask_valid_mems_allowed(ac->nodemask)) {
+ ac->nodemask = NULL;
+ return true;
+ }
+
+ /*
+ * When updating a task's mems_allowed or mempolicy nodemask, it is
+ * possible to race with parallel threads in such a way that our
+ * allocation can fail while the mask is being updated. If we are about
+ * to fail, check if the cpuset changed during allocation and if so,
+ * retry.
+ */
+ if (read_mems_allowed_retry(cpuset_mems_cookie))
+ return true;
+
+ return false;
+}
+
static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct alloc_context *ac)
@@ -3872,11 +3905,9 @@ retry:
&compaction_retries))
goto retry;
- /*
- * It's possible we raced with cpuset update so the OOM would be
- * premature (see below the nopage: label for full explanation).
- */
- if (read_mems_allowed_retry(cpuset_mems_cookie))
+
+ /* Deal with possible cpuset update races before we start OOM killing */
+ if (check_retry_cpuset(cpuset_mems_cookie, ac))
goto retry_cpuset;
/* Reclaim has failed us, start killing things */
@@ -3897,14 +3928,8 @@ retry:
}
nopage:
- /*
- * When updating a task's mems_allowed or mempolicy nodemask, it is
- * possible to race with parallel threads in such a way that our
- * allocation can fail while the mask is being updated. If we are about
- * to fail, check if the cpuset changed during allocation and if so,
- * retry.
- */
- if (read_mems_allowed_retry(cpuset_mems_cookie))
+ /* Deal with possible cpuset update races before we fail */
+ if (check_retry_cpuset(cpuset_mems_cookie, ac))
goto retry_cpuset;
/*