[PATCH 2/3] mm/oom_kill: introduce is_sysrq_oom helper

From: Yaowei Bai
Date: Wed Sep 16 2015 - 08:17:43 EST


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

No functional changes.

Signed-off-by: Yaowei Bai <bywxiaobai@xxxxxxx>
---
mm/oom_kill.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1ecc0bc..7b6228e 100644
--- 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");
}
--
1.9.1


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