mm/oom_kill.c: introduce is_sysrq_oom helper

Introduce is_sysrq_oom helper function indicating oom kill triggered
by sysrq to improve readability.

No functional changes.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1ecc0bcaecc518458765347f8b0fa5d5eed46f75..7b6228efb7b44a1bacd3416baa1b535abb05ea7c 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -118,6 +118,15 @@ found:
        return t;
 }
 
+/*
+ * order == -1 means the oom kill is required by sysrq, otherwise only
+ * for display purposes.
+ */
+static inline bool is_sysrq_oom(struct oom_control *oc)
+{
+       return oc->order == -1;
+}
+
 /* return true if the task is not adequate as candidate victim task. */
 static bool oom_unkillable_task(struct task_struct *p,
                struct mem_cgroup *memcg, const nodemask_t *nodemask)
@@ -265,7 +274,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
         * Don't allow any other task to have access to the reserves.
         */
        if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
-               if (oc->order != -1)
+               if (!is_sysrq_oom(oc))
                        return OOM_SCAN_ABORT;
        }
        if (!task->mm)
@@ -278,7 +287,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
        if (oom_task_origin(task))
                return OOM_SCAN_SELECT;
 
-       if (task_will_free_mem(task) && oc->order != -1)
+       if (task_will_free_mem(task) && !is_sysrq_oom(oc))
                return OOM_SCAN_ABORT;
 
        return OOM_SCAN_OK;
@@ -608,7 +617,7 @@ void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint,
                        return;
        }
        /* Do not panic for oom kills triggered by sysrq */
-       if (oc->order == -1)
+       if (is_sysrq_oom(oc))
                return;
        dump_header(oc, NULL, memcg);
        panic("Out of memory: %s panic_on_oom is enabled\n",
@@ -688,7 +697,7 @@ bool out_of_memory(struct oom_control *oc)
 
        p = select_bad_process(oc, &points, totalpages);
        /* Found nothing?!?! Either we hang forever, or we panic. */
-       if (!p && oc->order != -1) {
+       if (!p && !is_sysrq_oom(oc)) {
                dump_header(oc, NULL, NULL);
                panic("Out of memory and no killable processes...\n");
        }