[Devel] [PATCH RH7] memcontrol: debug for hang in mem_cgroup_reparent_charges

[Pavel Tikhomirov]

This adds a soft_timeout of 1 min, if we hit it then debug message would
be printed to show for how many minutes we are hanging, and soft_timeout
is reset to be triggered in 1 min again, until we reach hard timeout.

This should probably be posible as RK patch.

https://jira.sw.ru/browse/PSBM-139206

Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 mm/memcontrol.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index aa933c25733f..cb5bdc05f2ca 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4596,6 +4596,8 @@ static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
 	/* Protection from leaked memcg->memory counter. */
 	unsigned long start_time = jiffies;
 	unsigned long timeout = start_time + HZ*1200;
+	unsigned long soft_timeout = start_time + HZ*60;
+	unsigned long num_soft_timeout = 0;
 	unsigned long mem, kmem;
 
 	do {
@@ -4637,6 +4639,16 @@ static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
 		 */
 		smp_rmb();
 		kmem = page_counter_read(&memcg->kmem);
+
+		if (time_after(jiffies, soft_timeout)) {
+			while (time_after(jiffies, soft_timeout)) {
+				soft_timeout += HZ*60;
+				num_soft_timeout++;
+			}
+
+			printk("mem_cgroup_reparent_charges: hang for %lu minutes\n",
+			       num_soft_timeout++);
+		}
 	} while ((mem - kmem > 0) && time_before(jiffies, timeout));
 
 	WARN_ONCE((mem - kmem > 0),
-- 
2.35.1