mm/oom_kill: squashed reverts to a stable state

Revert "mm, oom: fix use-after-free in oom_kill_process"

This reverts commit e1bebdeedb497f03d426c85a89c3807c7e75268d.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm,oom: make oom_killer_disable() killable"

This reverts commit 65a7400a432639aa8d5e572f30687fbca204b6f8.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm: oom_kill: don't ignore oom score on exiting tasks"

This reverts commit d60dae46b27a8f381e4a7ad9dde870faa49fa5f1.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm/oom_kill.c: avoid attempting to kill init sharing same memory"

This reverts commit 10773c0325259d6640b93c0694b5598ddf84939f.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "CHROMIUM: DROP: mm/oom_kill: Double-check before killing a child in our place"

This reverts commit 2bdd9a2042a0e12d96c545773d9d8038c920f813.

Revert "mm/oom_kill: fix the wrong task->mm == mm checks in oom_kill_process()"

This reverts commit 419a313435b31821e4d045ca4b7ea1cc5fa02035.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm/oom_kill: cleanup the "kill sharing same memory" loop"

This reverts commit afda78c6de38f9f66eba0955153b380d540d8276.

Revert "mm/oom_kill: remove the wrong fatal_signal_pending() check in oom_kill_process()"

This reverts commit acde9c2ace298b249c06ec5b0b971c333449dc09.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm, oom: remove task_lock protecting comm printing"

This reverts commit 9a9ca142d250ec9de1215284857f4528c6ddb080.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm/oom_kill.c: suppress unnecessary "sharing same memory" message"

This reverts commit 1aa2960f7c70d65b1481f805ac73b988faff6747.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm/oom_kill.c: reverse the order of setting TIF_MEMDIE and sending SIGKILL"

This reverts commit f028aedfcfd2e2bb98921b98d3ae183387ab8fed.

Revert "mm, oom: remove unnecessary variable"

This reverts commit 54b0b58224146d68a11bccb5e64683ab3029373a.

Revert "mm/oom_kill.c: print points as unsigned int"

This reverts commit 603f975a6d4f0b56c7f6df7889ef2a704eca94a3.

Signed-off-by: Corinna Vinschen <xda@vinschen.de>

Revert "mm: oom_kill: simplify OOM killer locking"

This reverts commit 7951a52ed35d162063fa08b27894e302fd716ccd.

Revert "mm: oom_kill: remove unnecessary locking in exit_oom_victim()"

This reverts commit f0739b25ac884682865d6aae7485e79489107bfb.

Revert "mm: oom_kill: generalize OOM progress waitqueue"

This reverts commit eb4b1243c72ba0b392bbe05dbf9f91959f70eb18.

Revert "mm: oom_kill: switch test-and-clear of known TIF_MEMDIE to clear"

This reverts commit e611f16275c3642cb8a6345ff2470926fef52110.

Revert "mm: oom_kill: clean up victim marking and exiting interfaces"

This reverts commit c6fada01b9370e3d7603b4ad8c26b56759174667.

Revert "mm: oom_kill: remove unnecessary locking in oom_enable()"

This reverts commit 5dd152d7351b3805f59b2b1f624722ab2f3c5fd8.

Revert "oom, PM: make OOM detection in the freezer path raceless"

This reverts commit 5fc5b1ddee5404a7629dd7045f54eaf8941bc11c.

3 files changed, 52 insertions, 20 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f3a417c1d..ab0be4565 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2601,26 +2601,28 @@ int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 #define CPUSET_NODELIST_LEN	(256)
 
 /**
- * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
+ * cpuset_print_task_mems_allowed - prints task's cpuset and mems_allowed
+ * @task: pointer to task_struct of some task.
  *
- * Description: Prints current's name, cpuset name, and cached copy of its
- * mems_allowed to the kernel log.
+ * Description: Prints @task's name, cpuset name, and cached copy of its
+ * mems_allowed to the kernel log.  Must hold task_lock(task) to allow
+ * dereferencing task_cs(task).
  */
-void cpuset_print_current_mems_allowed(void)
+void cpuset_print_task_mems_allowed(struct task_struct *tsk)
 {
 	 /* Statically allocated to prevent using excess stack. */
 	static char cpuset_nodelist[CPUSET_NODELIST_LEN];
 	static DEFINE_SPINLOCK(cpuset_buffer_lock);
 
-	struct cgroup *cgrp = task_cs(current)->css.cgroup;
+	struct cgroup *cgrp = task_cs(tsk)->css.cgroup;
 
 	rcu_read_lock();
 	spin_lock(&cpuset_buffer_lock);
 
 	nodelist_scnprintf(cpuset_nodelist, CPUSET_NODELIST_LEN,
-			   current->mems_allowed);
-	pr_info("%s cpuset=%s mems_allowed=%s\n",
-	       current->comm, cgroup_name(cgrp), cpuset_nodelist);
+			   tsk->mems_allowed);
+	printk(KERN_INFO "%s cpuset=%s mems_allowed=%s\n",
+	       tsk->comm, cgroup_name(cgrp), cpuset_nodelist);
 
 	spin_unlock(&cpuset_buffer_lock);
 	rcu_read_unlock();
diff --git a/kernel/exit.c b/kernel/exit.c
index d9153652a..dffb92e9b 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -458,10 +458,8 @@ static void exit_mm(struct task_struct *tsk)
 	enter_lazy_tlb(mm, current);
 	task_unlock(tsk);
 	mm_update_next_owner(mm);
-
 	mmput(mm);
-	if (test_thread_flag(TIF_MEMDIE))
-		exit_oom_victim();
+	unmark_oom_victim();
 }
 
 static struct task_struct *find_alive_thread(struct task_struct *p)
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 899e07479..3bd3a1185 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -118,6 +118,30 @@ static int try_to_freeze_tasks(bool user_only)
 	return todo ? -EBUSY : 0;
 }
 
+static bool __check_frozen_processes(void)
+{
+	struct task_struct *g, *p;
+
+	for_each_process_thread(g, p)
+		if (p != current && !freezer_should_skip(p) && !frozen(p))
+			return false;
+
+	return true;
+}
+
+/*
+ * Returns true if all freezable tasks (except for current) are frozen already
+ */
+static bool check_frozen_processes(void)
+{
+	bool ret;
+
+	read_lock(&tasklist_lock);
+	ret = __check_frozen_processes();
+	read_unlock(&tasklist_lock);
+	return ret;
+}
+
 /**
  * freeze_processes - Signal user space processes to enter the refrigerator.
  * The current thread will not be frozen.  The same process that calls
@@ -128,6 +152,7 @@ static int try_to_freeze_tasks(bool user_only)
 int freeze_processes(void)
 {
 	int error;
+	int oom_kills_saved;
 
 	error = __usermodehelper_disable(UMH_FREEZING);
 	if (error)
@@ -142,22 +167,29 @@ int freeze_processes(void)
 	pm_wakeup_clear();
 	pr_info("Freezing user space processes ... ");
 	pm_freezing = true;
+	oom_kills_saved = oom_kills_count();
 	error = try_to_freeze_tasks(true);
 	if (!error) {
 		__usermodehelper_set_disable_depth(UMH_DISABLED);
-		pr_cont("done.");
+		oom_killer_disable();
+
+		/*
+		 * There might have been an OOM kill while we were
+		 * freezing tasks and the killed task might be still
+		 * on the way out so we have to double check for race.
+		 */
+		if (oom_kills_count() != oom_kills_saved &&
+		    !check_frozen_processes()) {
+			__usermodehelper_set_disable_depth(UMH_ENABLED);
+			pr_cont("OOM in progress.");
+			error = -EBUSY;
+		} else {
+			pr_cont("done.");
+		}
 	}
 	pr_cont("\n");
 	BUG_ON(in_atomic());
 
-	/*
-	 * Now that the whole userspace is frozen we need to disbale
-	 * the OOM killer to disallow any further interference with
-	 * killable tasks.
-	 */
-	if (!error && !oom_killer_disable())
-		error = -EBUSY;
-
 	if (error)
 		thaw_processes();
 	return error;