memcg: print cgroup information when system panics due to panic_on_oom

If kernel panics due to oom, caused by a cgroup reaching its limit, when
'compulsory panic_on_oom' is enabled, then we will only see that the OOM
happened because of "compulsory panic_on_oom is enabled" but this doesn't
tell the difference between mempolicy and memcg.  And dumping system wide
information is plain wrong and more confusing.  This patch provides the
information of the cgroup whose limit triggerred panic

Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan@mentor.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/oom.h b/include/linux/oom.h
index d5771bed59c92d995d7b9b8c97ea5976b42036a7..44b2f6f7bbd8323b6462417f769fc14e7cf37a2c 100644 (file)
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -66,7 +66,8 @@ extern bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_flags);
 extern void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_flags);
 
 extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
-                              int order, const nodemask_t *nodemask);
+                              int order, const nodemask_t *nodemask,
+                              struct mem_cgroup *memcg);
 
 extern enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
                unsigned long totalpages, const nodemask_t *nodemask,

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f227786e73db2fa7dd190cdba993bc0d53c42460..c3f09b2dda5f9cf00e4250e7b68745575bd806d1 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1442,15 +1442,17 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
        struct mem_cgroup *iter;
        unsigned int i;
 
-       if (!p)
-               return;
-
        mutex_lock(&oom_info_lock);
        rcu_read_lock();
 
-       pr_info("Task in ");
-       pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
-       pr_cont(" killed as a result of limit of ");
+       if (p) {
+               pr_info("Task in ");
+               pr_cont_cgroup_path(task_cgroup(p, memory_cgrp_id));
+               pr_cont(" killed as a result of limit of ");
+       } else {
+               pr_info("Memory limit reached of cgroup ");
+       }
+
        pr_cont_cgroup_path(memcg->css.cgroup);
        pr_cont("\n");
 
@@ -1537,7 +1539,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
                return;
        }
 
-       check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL);
+       check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, order, NULL, memcg);
        totalpages = mem_cgroup_get_limit(memcg) ? : 1;
        for_each_mem_cgroup_tree(iter, memcg) {
                struct css_task_iter it;

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 642f38cb175aa8321ab25d643d449d6cdd94f977..52628c819bf7d4852cc4604b89357e99420e6c74 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -612,7 +612,8 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
  * Determines whether the kernel must panic because of the panic_on_oom sysctl.
  */
 void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
-                       int order, const nodemask_t *nodemask)
+                       int order, const nodemask_t *nodemask,
+                       struct mem_cgroup *memcg)
 {
        if (likely(!sysctl_panic_on_oom))
                return;
@@ -625,7 +626,7 @@ void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
                if (constraint != CONSTRAINT_NONE)
                        return;
        }
-       dump_header(NULL, gfp_mask, order, NULL, nodemask);
+       dump_header(NULL, gfp_mask, order, memcg, nodemask);
        panic("Out of memory: %s panic_on_oom is enabled\n",
                sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
 }
@@ -740,7 +741,7 @@ static void __out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
        constraint = constrained_alloc(zonelist, gfp_mask, nodemask,
                                                &totalpages);
        mpol_mask = (constraint == CONSTRAINT_MEMORY_POLICY) ? nodemask : NULL;
-       check_panic_on_oom(constraint, gfp_mask, order, mpol_mask);
+       check_panic_on_oom(constraint, gfp_mask, order, mpol_mask, NULL);
 
        if (sysctl_oom_kill_allocating_task && current->mm &&
            !oom_unkillable_task(current, NULL, nodemask) &&