On Wed 16-09-15 19:59:59, Yaowei Bai wrote:
> Introduce is_sysrq_oom helper function indicating oom kill triggered
> by sysrq to improve readability.
>
> No functional changes.
I was complaining about a subtle semantic of order -1 when it was
introduced. This is easier to follow. At least for me.
> Signed-off-by: Yaowei Bai <bywxiaobai@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> 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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--
Michal Hocko
SUSE Labs
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