Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:

 - the rest of MM

 - KASAN updates

 - procfs updates

 - exit, fork updates

 - printk updates

 - lib/ updates

 - radix-tree testsuite updates

 - checkpatch updates

 - kprobes updates

 - a few other misc bits

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (162 commits)
  samples/kprobes: print out the symbol name for the hooks
  samples/kprobes: add a new module parameter
  kprobes: add the "tls" argument for j_do_fork
  init/main.c: simplify initcall_blacklisted()
  fs/efs/super.c: fix return value
  checkpatch: improve --git <commit-count> shortcut
  checkpatch: reduce number of `git log` calls with --git
  checkpatch: add support to check already applied git commits
  checkpatch: add --list-types to show message types to show or ignore
  checkpatch: advertise the --fix and --fix-inplace options more
  checkpatch: whine about ACCESS_ONCE
  checkpatch: add test for keywords not starting on tabstops
  checkpatch: improve CONSTANT_COMPARISON test for structure members
  checkpatch: add PREFER_IS_ENABLED test
  lib/GCD.c: use binary GCD algorithm instead of Euclidean
  radix-tree: free up the bottom bit of exceptional entries for reuse
  dax: move RADIX_DAX_ definitions to dax.c
  radix-tree: make radix_tree_descend() more useful
  radix-tree: introduce radix_tree_replace_clear_tags()
  radix-tree: tidy up __radix_tree_create()
  ...

1 files changed, 19 insertions, 15 deletions

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 415f7eb913fa..5bb2f7698ad7 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -174,8 +174,13 @@ unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
 	if (!p)
 		return 0;
 
+	/*
+	 * Do not even consider tasks which are explicitly marked oom
+	 * unkillable or have been already oom reaped.
+	 */
 	adj = (long)p->signal->oom_score_adj;
-	if (adj == OOM_SCORE_ADJ_MIN) {
+	if (adj == OOM_SCORE_ADJ_MIN ||
+			test_bit(MMF_OOM_REAPED, &p->mm->flags)) {
 		task_unlock(p);
 		return 0;
 	}
@@ -278,12 +283,8 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
 	 * This task already has access to memory reserves and is being killed.
 	 * Don't allow any other task to have access to the reserves.
 	 */
-	if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
-		if (!is_sysrq_oom(oc))
-			return OOM_SCAN_ABORT;
-	}
-	if (!task->mm)
-		return OOM_SCAN_CONTINUE;
+	if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims))
+		return OOM_SCAN_ABORT;
 
 	/*
 	 * If task is allocating a lot of memory and has been marked to be
@@ -302,12 +303,12 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
 static struct task_struct *select_bad_process(struct oom_control *oc,
 		unsigned int *ppoints, unsigned long totalpages)
 {
-	struct task_struct *g, *p;
+	struct task_struct *p;
 	struct task_struct *chosen = NULL;
 	unsigned long chosen_points = 0;
 
 	rcu_read_lock();
-	for_each_process_thread(g, p) {
+	for_each_process(p) {
 		unsigned int points;
 
 		switch (oom_scan_process_thread(oc, p, totalpages)) {
@@ -326,9 +327,6 @@ static struct task_struct *select_bad_process(struct oom_control *oc,
 		points = oom_badness(p, NULL, oc->nodemask, totalpages);
 		if (!points || points < chosen_points)
 			continue;
-		/* Prefer thread group leaders for display purposes */
-		if (points == chosen_points && thread_group_leader(chosen))
-			continue;
 
 		chosen = p;
 		chosen_points = points;
@@ -441,7 +439,6 @@ static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);
 static struct task_struct *oom_reaper_list;
 static DEFINE_SPINLOCK(oom_reaper_lock);
 
-
 static bool __oom_reap_task(struct task_struct *tsk)
 {
 	struct mmu_gather tlb;
@@ -513,9 +510,14 @@ static bool __oom_reap_task(struct task_struct *tsk)
 	 * This task can be safely ignored because we cannot do much more
 	 * to release its memory.
 	 */
-	tsk->signal->oom_score_adj = OOM_SCORE_ADJ_MIN;
+	set_bit(MMF_OOM_REAPED, &mm->flags);
 out:
-	mmput(mm);
+	/*
+	 * Drop our reference but make sure the mmput slow path is called from a
+	 * different context because we shouldn't risk we get stuck there and
+	 * put the oom_reaper out of the way.
+	 */
+	mmput_async(mm);
 	return ret;
 }
 
@@ -664,6 +666,7 @@ void mark_oom_victim(struct task_struct *tsk)
 	/* OOM killer might race with memcg OOM */
 	if (test_and_set_tsk_thread_flag(tsk, TIF_MEMDIE))
 		return;
+	atomic_inc(&tsk->signal->oom_victims);
 	/*
 	 * Make sure that the task is woken up from uninterruptible sleep
 	 * if it is frozen because OOM killer wouldn't be able to free
@@ -681,6 +684,7 @@ void exit_oom_victim(struct task_struct *tsk)
 {
 	if (!test_and_clear_tsk_thread_flag(tsk, TIF_MEMDIE))
 		return;
+	atomic_dec(&tsk->signal->oom_victims);
 
 	if (!atomic_dec_return(&oom_victims))
 		wake_up_all(&oom_victims_wait);