memcg: avoid unnecessary system-wide-oom-killer

Current mmtom has new oom function as pagefault_out_of_memory().  It's
added for select bad process rathar than killing current.

When memcg hit limit and calls OOM at page_fault, this handler called and
system-wide-oom handling happens.  (means kernel panics if panic_on_oom is
true....)

To avoid overkill, check memcg's recent behavior before starting
system-wide-oom.

And this patch also fixes to guarantee "don't accnout against process with
TIF_MEMDIE".  This is necessary for smooth OOM.

[akpm@linux-foundation.org: build fix]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Jan Blunck <jblunck@suse.de>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 37 insertions, 4 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 886e2224c5fd..659b0c58f13e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -153,7 +153,7 @@ struct mem_cgroup {
          * Should the accounting and control be hierarchical, per subtree?
          */
         bool use_hierarchy;
-
+        unsigned long   last_oom_jiffies;
         int             obsolete;
         atomic_t        refcnt;
         /*
@@ -615,6 +615,22 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
         return ret;
 }
 
+bool mem_cgroup_oom_called(struct task_struct *task)
+{
+        bool ret = false;
+        struct mem_cgroup *mem;
+        struct mm_struct *mm;
+
+        rcu_read_lock();
+        mm = task->mm;
+        if (!mm)
+                mm = &init_mm;
+        mem = mem_cgroup_from_task(rcu_dereference(mm->owner));
+        if (mem && time_before(jiffies, mem->last_oom_jiffies + HZ/10))
+                ret = true;
+        rcu_read_unlock();
+        return ret;
+}
 /*
  * Unlike exported interface, "oom" parameter is added. if oom==true,
  * oom-killer can be invoked.
@@ -626,6 +642,13 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
         struct mem_cgroup *mem, *mem_over_limit;
         int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
         struct res_counter *fail_res;
+
+        if (unlikely(test_thread_flag(TIF_MEMDIE))) {
+                /* Don't account this! */
+                *memcg = NULL;
+                return 0;
+        }
+
         /*
          * We always charge the cgroup the mm_struct belongs to.
          * The mm_struct's mem_cgroup changes on task migration if the
@@ -694,8 +717,10 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm,
                         continue;
 
                 if (!nr_retries--) {
-                        if (oom)
+                        if (oom) {
                                 mem_cgroup_out_of_memory(mem, gfp_mask);
+                                mem->last_oom_jiffies = jiffies;
+                        }
                         goto nomem;
                 }
         }
@@ -832,7 +857,7 @@ static int mem_cgroup_move_parent(struct page_cgroup *pc,
 
 
         ret = __mem_cgroup_try_charge(NULL, gfp_mask, &parent, false);
-        if (ret)
+        if (ret || !parent)
                 return ret;
 
         if (!get_page_unless_zero(page))
@@ -883,7 +908,7 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
 
         mem = memcg;
         ret = __mem_cgroup_try_charge(mm, gfp_mask, &mem, true);
-        if (ret)
+        if (ret || !mem)
                 return ret;
 
         __mem_cgroup_commit_charge(mem, pc, ctype);
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 6b9e758c98a5..fd150e3a2567 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -560,6 +560,13 @@ void pagefault_out_of_memory(void)
                 /* Got some memory back in the last second. */
                 return;
 
+        /*
+         * If this is from memcg, oom-killer is already invoked.
+         * and not worth to go system-wide-oom.
+         */
+        if (mem_cgroup_oom_called(current))
+                goto rest_and_return;
+
         if (sysctl_panic_on_oom)
                 panic("out of memory from page fault. panic_on_oom is selected.\n");
 
@@ -571,6 +578,7 @@ void pagefault_out_of_memory(void)
          * Give "p" a good chance of killing itself before we
          * retry to allocate memory.
          */
+rest_and_return:
         if (!test_thread_flag(TIF_MEMDIE))
                 schedule_timeout_uninterruptible(1);
 }