[-mm patch] Show memcg information during OOM

[Balbir Singh]

Hi, All,

I found the following patch useful while debugging the memory
controller. It adds additional information if memcg invoked the OOM.

Comments, Suggestions?

From: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>

Description: Add RSS and swap to OOM output from memcg

This patch displays memcg values like failcnt, usage and limit
when an OOM occurs due to memcg.

Signed-off-by: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
---

 include/linux/memcontrol.h |    5 +++++
 mm/memcontrol.c            |   15 +++++++++++++++
 mm/oom_kill.c              |    1 +
 3 files changed, 21 insertions(+), 0 deletions(-)


diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 326f45c..2ce1737 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -104,6 +104,7 @@ struct zone_reclaim_stat *mem_cgroup_get_reclaim_stat(struct mem_cgroup *memcg,
 						      struct zone *zone);
 struct zone_reclaim_stat*
 mem_cgroup_get_reclaim_stat_from_page(struct page *page);
+extern void mem_cgroup_print_mem_info(struct mem_cgroup *memcg);
 
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 extern int do_swap_account;
@@ -270,6 +271,10 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
 	return NULL;
 }
 
+void mem_cgroup_print_mem_info(struct mem_cgroup *memcg)
+{
+}
+
 #endif /* CONFIG_CGROUP_MEM_CONT */
 
 #endif /* _LINUX_MEMCONTROL_H */
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8e4be9c..75eae85 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -813,6 +813,21 @@ bool mem_cgroup_oom_called(struct task_struct *task)
 	rcu_read_unlock();
 	return ret;
 }
+
+void mem_cgroup_print_mem_info(struct mem_cgroup *memcg)
+{
+	printk(KERN_WARNING "Memory cgroups's name %s\n",
+		memcg->css.cgroup->dentry->d_name.name);
+	printk(KERN_WARNING "Memory cgroup RSS : usage %llu, limit %llu"
+		" failcnt %llu\n", res_counter_read_u64(&memcg->res, RES_USAGE),
+		res_counter_read_u64(&memcg->res, RES_LIMIT),
+		res_counter_read_u64(&memcg->res, RES_FAILCNT));
+	printk(KERN_WARNING "Memory cgroup swap: usage %llu, limit %llu "
+		"failcnt %llu\n", res_counter_read_u64(&memcg->res, RES_USAGE),
+		res_counter_read_u64(&memcg->res, RES_LIMIT),
+		res_counter_read_u64(&memcg->res, RES_FAILCNT));
+}
+
 /*
  * Unlike exported interface, "oom" parameter is added. if oom==true,
  * oom-killer can be invoked.
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index d3b9bac..b8e53ae 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -392,6 +392,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 			current->comm, gfp_mask, order, current->oomkilladj);
 		task_lock(current);
 		cpuset_print_task_mems_allowed(current);
+		mem_cgroup_print_mem_info(mem);
 		task_unlock(current);
 		dump_stack();
 		show_mem();

-- 
	Balbir
--
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