One of the largest chunks of log messages in a OOM is from dump_stack() and in
some cases it isn't even necessary to figure out what's going on. In
systems with multiple tenants/containers with limited resources each
OOMs can be way more frequent and being able to reduce the amount of log
output for each situation is useful.
This patch adds a sysctl to allow disabling dump_stack() during an OOM while
keeping the default to behave the same way it behaves today.
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: cgroups@xxxxxxxxxxxxxxx
Signed-off-by: Aristeu Rozanski <arozansk@xxxxxxxxxx>
---
include/linux/oom.h | 1 +
kernel/sysctl.c | 7 +++++++
mm/oom_kill.c | 4 +++-
3 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 03e6257..bdd03e5 100644
--- 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
--
1.8.3.1
--
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