Merge branch 'akpm' (patches from Andrew)

Pull updates from Andrew Morton:
 "A few fixes and stragglers.

  Subsystems affected by this patch series: mm/memory-failure, ocfs2,
  lib/lzo, misc"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  amdgpu: a NULL ->mm does not mean a thread is a kthread
  lib/lzo: fix ambiguous encoding bug in lzo-rle
  ocfs2: fix build failure when TCP/IP is disabled
  mm/memory-failure: send SIGBUS(BUS_MCEERR_AR) only to current thread
  mm/memory-failure: prioritize prctl(PR_MCE_KILL) over vm.memory_failure_early_kill

1 files changed, 26 insertions, 17 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ababa368cb68..47b8ccb1fb9b 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -212,15 +212,13 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
 	short addr_lsb = tk->size_shift;
 	int ret = 0;
 
-	if ((t->mm == current->mm) || !(flags & MF_ACTION_REQUIRED))
-		pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
+	pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
 			pfn, t->comm, t->pid);
 
 	if (flags & MF_ACTION_REQUIRED) {
-		if (t->mm == current->mm)
-			ret = force_sig_mceerr(BUS_MCEERR_AR,
+		WARN_ON_ONCE(t != current);
+		ret = force_sig_mceerr(BUS_MCEERR_AR,
 					 (void __user *)tk->addr, addr_lsb);
-		/* send no signal to non-current processes */
 	} else {
 		/*
 		 * Don't use force here, it's convenient if the signal
@@ -402,9 +400,15 @@ static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
 {
 	struct task_struct *t;
 
-	for_each_thread(tsk, t)
-		if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY))
-			return t;
+	for_each_thread(tsk, t) {
+		if (t->flags & PF_MCE_PROCESS) {
+			if (t->flags & PF_MCE_EARLY)
+				return t;
+		} else {
+			if (sysctl_memory_failure_early_kill)
+				return t;
+		}
+	}
 	return NULL;
 }
 
@@ -413,21 +417,26 @@ static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
  * to be signaled when some page under the process is hwpoisoned.
  * Return task_struct of the dedicated thread (main thread unless explicitly
  * specified) if the process is "early kill," and otherwise returns NULL.
+ *
+ * Note that the above is true for Action Optional case, but not for Action
+ * Required case where SIGBUS should sent only to the current thread.
  */
 static struct task_struct *task_early_kill(struct task_struct *tsk,
 					   int force_early)
 {
-	struct task_struct *t;
 	if (!tsk->mm)
 		return NULL;
-	if (force_early)
-		return tsk;
-	t = find_early_kill_thread(tsk);
-	if (t)
-		return t;
-	if (sysctl_memory_failure_early_kill)
-		return tsk;
-	return NULL;
+	if (force_early) {
+		/*
+		 * Comparing ->mm here because current task might represent
+		 * a subthread, while tsk always points to the main thread.
+		 */
+		if (tsk->mm == current->mm)
+			return current;
+		else
+			return NULL;
+	}
+	return find_early_kill_thread(tsk);
 }
 
 /*