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-rw-r--r--mm/oom_kill.c111
1 files changed, 65 insertions, 46 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index e6c10640e56b..f8eba9651c0c 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -288,6 +288,59 @@ static enum oom_constraint constrained_alloc(struct zonelist *zonelist,
}
#endif
+enum oom_scan_t {
+ OOM_SCAN_OK, /* scan thread and find its badness */
+ OOM_SCAN_CONTINUE, /* do not consider thread for oom kill */
+ OOM_SCAN_ABORT, /* abort the iteration and return */
+ OOM_SCAN_SELECT, /* always select this thread first */
+};
+
+static enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
+ struct mem_cgroup *memcg, unsigned long totalpages,
+ const nodemask_t *nodemask, bool force_kill)
+{
+ if (task->exit_state)
+ return OOM_SCAN_CONTINUE;
+ if (oom_unkillable_task(task, memcg, nodemask))
+ return OOM_SCAN_CONTINUE;
+
+ /*
+ * This task already has access to memory reserves and is being killed.
+ * Don't allow any other task to have access to the reserves.
+ */
+ if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
+ if (unlikely(frozen(task)))
+ __thaw_task(task);
+ if (!force_kill)
+ return OOM_SCAN_ABORT;
+ }
+ if (!task->mm)
+ return OOM_SCAN_CONTINUE;
+
+ if (task->flags & PF_EXITING) {
+ /*
+ * If task is current and is in the process of releasing memory,
+ * allow the "kill" to set TIF_MEMDIE, which will allow it to
+ * access memory reserves. Otherwise, it may stall forever.
+ *
+ * The iteration isn't broken here, however, in case other
+ * threads are found to have already been oom killed.
+ */
+ if (task == current)
+ return OOM_SCAN_SELECT;
+ else if (!force_kill) {
+ /*
+ * If this task is not being ptraced on exit, then wait
+ * for it to finish before killing some other task
+ * unnecessarily.
+ */
+ if (!(task->group_leader->ptrace & PT_TRACE_EXIT))
+ return OOM_SCAN_ABORT;
+ }
+ }
+ return OOM_SCAN_OK;
+}
+
/*
* Simple selection loop. We chose the process with the highest
* number of 'points'. We expect the caller will lock the tasklist.
@@ -305,53 +358,19 @@ static struct task_struct *select_bad_process(unsigned int *ppoints,
do_each_thread(g, p) {
unsigned int points;
- if (p->exit_state)
- continue;
- if (oom_unkillable_task(p, memcg, nodemask))
- continue;
-
- /*
- * This task already has access to memory reserves and is
- * being killed. Don't allow any other task access to the
- * memory reserve.
- *
- * Note: this may have a chance of deadlock if it gets
- * blocked waiting for another task which itself is waiting
- * for memory. Is there a better alternative?
- */
- if (test_tsk_thread_flag(p, TIF_MEMDIE)) {
- if (unlikely(frozen(p)))
- __thaw_task(p);
- if (!force_kill)
- return ERR_PTR(-1UL);
- }
- if (!p->mm)
+ switch (oom_scan_process_thread(p, memcg, totalpages, nodemask,
+ force_kill)) {
+ case OOM_SCAN_SELECT:
+ chosen = p;
+ chosen_points = ULONG_MAX;
+ /* fall through */
+ case OOM_SCAN_CONTINUE:
continue;
-
- if (p->flags & PF_EXITING) {
- /*
- * If p is the current task and is in the process of
- * releasing memory, we allow the "kill" to set
- * TIF_MEMDIE, which will allow it to gain access to
- * memory reserves. Otherwise, it may stall forever.
- *
- * The loop isn't broken here, however, in case other
- * threads are found to have already been oom killed.
- */
- if (p == current) {
- chosen = p;
- chosen_points = ULONG_MAX;
- } else if (!force_kill) {
- /*
- * If this task is not being ptraced on exit,
- * then wait for it to finish before killing
- * some other task unnecessarily.
- */
- if (!(p->group_leader->ptrace & PT_TRACE_EXIT))
- return ERR_PTR(-1UL);
- }
- }
-
+ case OOM_SCAN_ABORT:
+ return ERR_PTR(-1UL);
+ case OOM_SCAN_OK:
+ break;
+ };
points = oom_badness(p, memcg, nodemask, totalpages);
if (points > chosen_points) {
chosen = p;