From f2a7a3f99bb7b34e15307d69bfe2b720823c8132 Mon Sep 17 00:00:00 2001
From: David Rientjes <rientjes@google.com>
Date: Mon, 9 Aug 2010 17:18:54 -0700
Subject: [PATCH] --- yaml --- r: 207215 b: refs/heads/master c:
 309ed882508cc471320ff79265e7340774d6746c h: refs/heads/master i:   207213:
 c87b2ecf5ddc03f5f024b1ac0878fdd4f39e99a3   207211:
 f21041095875590ac1596f2ae9017d76e4974cc5   207207:
 20060597e1c1408c7dc5c44c4fee904154decd92   207199:
 b8e849a3885753eb501d242d18a6644156991207 v: v3

---
 [refs]                    |  2 +-
 trunk/include/linux/oom.h |  1 +
 trunk/mm/oom_kill.c       | 53 +++++++++++++++++++++------------------
 3 files changed, 31 insertions(+), 25 deletions(-)

diff --git a/[refs] b/[refs]
index 8c03daa37448..db100bc80882 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 03668b3ceb0c7a95e09f1b6169f5270ffc1a19f6
+refs/heads/master: 309ed882508cc471320ff79265e7340774d6746c
diff --git a/trunk/include/linux/oom.h b/trunk/include/linux/oom.h
index 537662315627..3ae6d94d0540 100644
--- a/trunk/include/linux/oom.h
+++ b/trunk/include/linux/oom.h
@@ -22,6 +22,7 @@ enum oom_constraint {
 	CONSTRAINT_NONE,
 	CONSTRAINT_CPUSET,
 	CONSTRAINT_MEMORY_POLICY,
+	CONSTRAINT_MEMCG,
 };
 
 extern int try_set_zone_oom(struct zonelist *zonelist, gfp_t gfp_flags);
diff --git a/trunk/mm/oom_kill.c b/trunk/mm/oom_kill.c
index 01b5e01e52cb..fca886d8b5fb 100644
--- a/trunk/mm/oom_kill.c
+++ b/trunk/mm/oom_kill.c
@@ -521,17 +521,40 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 	return oom_kill_task(victim);
 }
 
+/*
+ * Determines whether the kernel must panic because of the panic_on_oom sysctl.
+ */
+static void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,
+				int order)
+{
+	if (likely(!sysctl_panic_on_oom))
+		return;
+	if (sysctl_panic_on_oom != 2) {
+		/*
+		 * panic_on_oom == 1 only affects CONSTRAINT_NONE, the kernel
+		 * does not panic for cpuset, mempolicy, or memcg allocation
+		 * failures.
+		 */
+		if (constraint != CONSTRAINT_NONE)
+			return;
+	}
+	read_lock(&tasklist_lock);
+	dump_header(NULL, gfp_mask, order, NULL);
+	read_unlock(&tasklist_lock);
+	panic("Out of memory: %s panic_on_oom is enabled\n",
+		sysctl_panic_on_oom == 2 ? "compulsory" : "system-wide");
+}
+
 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
 void mem_cgroup_out_of_memory(struct mem_cgroup *mem, gfp_t gfp_mask)
 {
 	unsigned long points = 0;
 	struct task_struct *p;
 
-	if (sysctl_panic_on_oom == 2)
-		panic("out of memory(memcg). panic_on_oom is selected.\n");
+	check_panic_on_oom(CONSTRAINT_MEMCG, gfp_mask, 0);
 	read_lock(&tasklist_lock);
 retry:
-	p = select_bad_process(&points, mem, CONSTRAINT_NONE, NULL);
+	p = select_bad_process(&points, mem, CONSTRAINT_MEMCG, NULL);
 	if (!p || PTR_ERR(p) == -1UL)
 		goto out;
 
@@ -632,8 +655,8 @@ static void __out_of_memory(gfp_t gfp_mask, int order,
 
 	/* Found nothing?!?! Either we hang forever, or we panic. */
 	if (!p) {
-		read_unlock(&tasklist_lock);
 		dump_header(NULL, gfp_mask, order, NULL);
+		read_unlock(&tasklist_lock);
 		panic("Out of memory and no killable processes...\n");
 	}
 
@@ -655,9 +678,7 @@ void pagefault_out_of_memory(void)
 		/* Got some memory back in the last second. */
 		return;
 
-	if (sysctl_panic_on_oom)
-		panic("out of memory from page fault. panic_on_oom is selected.\n");
-
+	check_panic_on_oom(CONSTRAINT_NONE, 0, 0);
 	read_lock(&tasklist_lock);
 	/* unknown gfp_mask and order */
 	__out_of_memory(0, 0, CONSTRAINT_NONE, NULL);
@@ -704,29 +725,13 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 		return;
 	}
 
-	if (sysctl_panic_on_oom == 2) {
-		dump_header(NULL, gfp_mask, order, NULL);
-		panic("out of memory. Compulsory panic_on_oom is selected.\n");
-	}
-
 	/*
 	 * Check if there were limitations on the allocation (only relevant for
 	 * NUMA) that may require different handling.
 	 */
 	constraint = constrained_alloc(zonelist, gfp_mask, nodemask);
+	check_panic_on_oom(constraint, gfp_mask, order);
 	read_lock(&tasklist_lock);
-	if (unlikely(sysctl_panic_on_oom)) {
-		/*
-		 * panic_on_oom only affects CONSTRAINT_NONE, the kernel
-		 * should not panic for cpuset or mempolicy induced memory
-		 * failures.
-		 */
-		if (constraint == CONSTRAINT_NONE) {
-			dump_header(NULL, gfp_mask, order, NULL);
-			read_unlock(&tasklist_lock);
-			panic("Out of memory: panic_on_oom is enabled\n");
-		}
-	}
 	__out_of_memory(gfp_mask, order, constraint, nodemask);
 	read_unlock(&tasklist_lock);