Re: [PATCH] oom_kill: add option to disable dump_stack()

From: David Rientjes
Date: Tue Dec 01 2015 - 19:03:01 EST


On Tue, 1 Dec 2015, Andrew Morton wrote:

> > --- a/include/linux/oom.h
> > +++ b/include/linux/oom.h
> > @@ -115,6 +115,7 @@ static inline bool task_will_free_mem(struct task_struct *task)
> >
> > /* sysctls */
> > extern int sysctl_oom_dump_tasks;
> > +extern int sysctl_oom_dump_stack;
> > extern int sysctl_oom_kill_allocating_task;
> > extern int sysctl_panic_on_oom;
> > #endif /* _INCLUDE_LINUX_OOM_H */
> > diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> > index e69201d..c812523 100644
> > --- a/kernel/sysctl.c
> > +++ b/kernel/sysctl.c
> > @@ -1176,6 +1176,13 @@ static struct ctl_table vm_table[] = {
> > .proc_handler = proc_dointvec,
> > },
> > {
> > + .procname = "oom_dump_stack",
> > + .data = &sysctl_oom_dump_stack,
> > + .maxlen = sizeof(sysctl_oom_dump_stack),
> > + .mode = 0644,
> > + .proc_handler = proc_dointvec,
> > + },
> > + {
> > .procname = "overcommit_ratio",
> > .data = &sysctl_overcommit_ratio,
> > .maxlen = sizeof(sysctl_overcommit_ratio),
> > diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> > index 1ecc0bc..bdbf83b 100644
> > --- a/mm/oom_kill.c
> > +++ b/mm/oom_kill.c
> > @@ -42,6 +42,7 @@
> > int sysctl_panic_on_oom;
> > int sysctl_oom_kill_allocating_task;
> > int sysctl_oom_dump_tasks = 1;
> > +int sysctl_oom_dump_stack = 1;
> >
> > DEFINE_MUTEX(oom_lock);
> >
> > @@ -384,7 +385,8 @@ static void dump_header(struct oom_control *oc, struct task_struct *p,
> > current->signal->oom_score_adj);
> > cpuset_print_task_mems_allowed(current);
> > task_unlock(current);
> > - dump_stack();
> > + if (sysctl_oom_dump_stack)
> > + dump_stack();
> > if (memcg)
> > mem_cgroup_print_oom_info(memcg, p);
> > else
>
> The patch seems reasonable to me, but it's missing the required update
> to Documentation/sysctl/vm.txt.
>

Not sure why we'd want yet-another-sysctl for something that can trivially
filtered from the log, but owell.
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