Merge tag 'v4.15-rc1' into next-seccomp

Linux 4.15-rc1

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/oom.h b/include/linux/oom.h
index 8a266e2be5a6..01c91d874a57 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __INCLUDE_LINUX_OOM_H
 #define __INCLUDE_LINUX_OOM_H
 
@@ -6,6 +7,8 @@
 #include <linux/types.h>
 #include <linux/nodemask.h>
 #include <uapi/linux/oom.h>
+#include <linux/sched/coredump.h> /* MMF_* */
+#include <linux/mm.h> /* VM_FAULT* */
 
 struct zonelist;
 struct notifier_block;
@@ -63,6 +66,26 @@ static inline bool tsk_is_oom_victim(struct task_struct * tsk)
 	return tsk->signal->oom_mm;
 }
 
+/*
+ * Checks whether a page fault on the given mm is still reliable.
+ * This is no longer true if the oom reaper started to reap the
+ * address space which is reflected by MMF_UNSTABLE flag set in
+ * the mm. At that moment any !shared mapping would lose the content
+ * and could cause a memory corruption (zero pages instead of the
+ * original content).
+ *
+ * User should call this before establishing a page table entry for
+ * a !shared mapping and under the proper page table lock.
+ *
+ * Return 0 when the PF is safe VM_FAULT_SIGBUS otherwise.
+ */
+static inline int check_stable_address_space(struct mm_struct *mm)
+{
+	if (unlikely(test_bit(MMF_UNSTABLE, &mm->flags)))
+		return VM_FAULT_SIGBUS;
+	return 0;
+}
+
 extern unsigned long oom_badness(struct task_struct *p,
 		struct mem_cgroup *memcg, const nodemask_t *nodemask,
 		unsigned long totalpages);