Michal Hocko wrote:
> > I don't understand why you are talking about PF_WQ_WORKER case.
>
> Because that seems to be the reason to have it there as per your
> comment.
OK. Then, I will fold below change into my patch.
if (did_some_progress) {
no_progress_loops = 0;
+ /*
-+ * This schedule_timeout_*() serves as a guaranteed sleep for
-+ * PF_WQ_WORKER threads when __zone_watermark_ok() == false.
++ * Try to give the OOM killer/reaper/victims some time for
++ * releasing memory.
+ */
+ if (!tsk_is_oom_victim(current))
+ schedule_timeout_uninterruptible(1);
But Roman, my patch conflicts with your "mm, oom: cgroup-aware OOM killer" patch
in linux-next. And it seems to me that your patch contains a bug which leads to
premature memory allocation failure explained below.
@@ -1029,6 +1050,7 @@ bool out_of_memory(struct oom_control *oc)
{
unsigned long freed = 0;
enum oom_constraint constraint = CONSTRAINT_NONE;
+ bool delay = false; /* if set, delay next allocation attempt */
if (oom_killer_disabled)
return false;
@@ -1073,27 +1095,39 @@ bool out_of_memory(struct oom_control *oc)
current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) &&
current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
get_task_struct(current);
- oc->chosen = current;
+ oc->chosen_task = current;
oom_kill_process(oc, "Out of memory (oom_kill_allocating_task)");
return true;
}
+ if (mem_cgroup_select_oom_victim(oc)) {
/* mem_cgroup_select_oom_victim() returns true if select_victim_memcg() made
oc->chosen_memcg != NULL.
select_victim_memcg() makes oc->chosen_memcg = INFLIGHT_VICTIM if there is
inflight memcg. But oc->chosen_task remains NULL because it did not call
oom_evaluate_task(), didn't it? (And if it called oom_evaluate_task(),
put_task_struct() is missing here.) */
+ if (oom_kill_memcg_victim(oc)) {
/* oom_kill_memcg_victim() returns true if oc->chosen_memcg == INFLIGHT_VICTIM. */
+ delay = true;
+ goto out;
+ }
+ }
+
select_bad_process(oc);
/* Found nothing?!?! Either we hang forever, or we panic. */
- if (!oc->chosen && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
+ if (!oc->chosen_task && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
dump_header(oc, NULL);
panic("Out of memory and no killable processes...\n");
}
- if (oc->chosen && oc->chosen != (void *)-1UL) {
+ if (oc->chosen_task && oc->chosen_task != (void *)-1UL) {
oom_kill_process(oc, !is_memcg_oom(oc) ? "Out of memory" :
"Memory cgroup out of memory");
- /*
- * Give the killed process a good chance to exit before trying
- * to allocate memory again.
- */
- schedule_timeout_killable(1);
+ delay = true;
}
- return !!oc->chosen;
+
+out:
+ /*
+ * Give the killed process a good chance to exit before trying
+ * to allocate memory again.
+ */
+ if (delay)
+ schedule_timeout_killable(1);
+
/* out_of_memory() returns false because oc->chosen_task remains NULL. */
+ return !!oc->chosen_task;
}
Can we apply my patch prior to your "mm, oom: cgroup-aware OOM killer" patch
(which eliminates "delay" and "out:" from your patch) so that people can easily
backport my patch? Or, do you want to apply a fix (which eliminates "delay" and
"out:" from linux-next) prior to my patch?
