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-rw-r--r--mm/oom_kill.c86
1 files changed, 57 insertions, 29 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index fca886d8b5fb..dad13fc41f47 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -631,6 +631,44 @@ void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)
}
/*
+ * Try to acquire the oom killer lock for all system zones. Returns zero if a
+ * parallel oom killing is taking place, otherwise locks all zones and returns
+ * non-zero.
+ */
+static int try_set_system_oom(void)
+{
+ struct zone *zone;
+ int ret = 1;
+
+ spin_lock(&zone_scan_lock);
+ for_each_populated_zone(zone)
+ if (zone_is_oom_locked(zone)) {
+ ret = 0;
+ goto out;
+ }
+ for_each_populated_zone(zone)
+ zone_set_flag(zone, ZONE_OOM_LOCKED);
+out:
+ spin_unlock(&zone_scan_lock);
+ return ret;
+}
+
+/*
+ * Clears ZONE_OOM_LOCKED for all system zones so that failed allocation
+ * attempts or page faults may now recall the oom killer, if necessary.
+ */
+static void clear_system_oom(void)
+{
+ struct zone *zone;
+
+ spin_lock(&zone_scan_lock);
+ for_each_populated_zone(zone)
+ zone_clear_flag(zone, ZONE_OOM_LOCKED);
+ spin_unlock(&zone_scan_lock);
+}
+
+
+/*
* Must be called with tasklist_lock held for read.
*/
static void __out_of_memory(gfp_t gfp_mask, int order,
@@ -665,33 +703,6 @@ retry:
goto retry;
}
-/*
- * pagefault handler calls into here because it is out of memory but
- * doesn't know exactly how or why.
- */
-void pagefault_out_of_memory(void)
-{
- unsigned long freed = 0;
-
- blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
- if (freed > 0)
- /* Got some memory back in the last second. */
- return;
-
- check_panic_on_oom(CONSTRAINT_NONE, 0, 0);
- read_lock(&tasklist_lock);
- /* unknown gfp_mask and order */
- __out_of_memory(0, 0, CONSTRAINT_NONE, NULL);
- read_unlock(&tasklist_lock);
-
- /*
- * Give "p" a good chance of killing itself before we
- * retry to allocate memory.
- */
- if (!test_thread_flag(TIF_MEMDIE))
- schedule_timeout_uninterruptible(1);
-}
-
/**
* out_of_memory - kill the "best" process when we run out of memory
* @zonelist: zonelist pointer
@@ -708,7 +719,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
int order, nodemask_t *nodemask)
{
unsigned long freed = 0;
- enum oom_constraint constraint;
+ enum oom_constraint constraint = CONSTRAINT_NONE;
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
@@ -729,7 +740,8 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
* Check if there were limitations on the allocation (only relevant for
* NUMA) that may require different handling.
*/
- constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
+ if (zonelist)
+ constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
check_panic_on_oom(constraint, gfp_mask, order);
read_lock(&tasklist_lock);
__out_of_memory(gfp_mask, order, constraint, nodemask);
@@ -742,3 +754,19 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
if (!test_thread_flag(TIF_MEMDIE))
schedule_timeout_uninterruptible(1);
}
+
+/*
+ * The pagefault handler calls here because it is out of memory, so kill a
+ * memory-hogging task. If a populated zone has ZONE_OOM_LOCKED set, a parallel
+ * oom killing is already in progress so do nothing. If a task is found with
+ * TIF_MEMDIE set, it has been killed so do nothing and allow it to exit.
+ */
+void pagefault_out_of_memory(void)
+{
+ if (try_set_system_oom()) {
+ out_of_memory(NULL, 0, 0, NULL);
+ clear_system_oom();
+ }
+ if (!test_thread_flag(TIF_MEMDIE))
+ schedule_timeout_uninterruptible(1);
+}