[PATCH 1/2] mmu-mayfail

[Chris Wilson]

---
 include/linux/mmu_notifier.h | 7 +++++++
 mm/mmu_notifier.c            | 2 +-
 mm/rmap.c                    | 5 +++--
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 736f6918335e..504393abf256 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -48,6 +48,7 @@ enum mmu_notifier_event {
 };
 
 #define MMU_NOTIFIER_RANGE_BLOCKABLE (1 << 0)
+#define MMU_NOTIFIER_RANGE_MAYFAIL (1 << 1)
 
 struct mmu_notifier_ops {
 	/*
@@ -396,6 +397,12 @@ mmu_notifier_range_blockable(const struct mmu_notifier_range *range)
 	return (range->flags & MMU_NOTIFIER_RANGE_BLOCKABLE);
 }
 
+static inline bool
+mmu_notifier_range_mayfail(const struct mmu_notifier_range *range)
+{
+	return (range->flags & MMU_NOTIFIER_RANGE_MAYFAIL);
+}
+
 static inline void mmu_notifier_release(struct mm_struct *mm)
 {
 	if (mm_has_notifiers(mm))
diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 06852b896fa6..85e82006553f 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -493,7 +493,7 @@ static int mn_hlist_invalidate_range_start(
 			_ret = ops->invalidate_range_start(subscription, range);
 			if (!mmu_notifier_range_blockable(range))
 				non_block_end();
-			if (_ret) {
+			if (_ret && !mmu_notifier_range_mayfail(range)) {
 				pr_info("%pS callback failed with %d in %sblockable context.\n",
 					ops->invalidate_range_start, _ret,
 					!mmu_notifier_range_blockable(range) ?
diff --git a/mm/rmap.c b/mm/rmap.c
index f79a206b271a..95f1820d5982 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1395,8 +1395,9 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 	 * Note that the page can not be free in this function as call of
 	 * try_to_unmap() must hold a reference on the page.
 	 */
-	mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
-				address,
+	mmu_notifier_range_init(&range,
+				MMU_NOTIFY_CLEAR, MMU_NOTIFIER_RANGE_MAYFAIL,
+				vma, vma->vm_mm, address,
 				min(vma->vm_end, address + page_size(page)));
 	if (PageHuge(page)) {
 		/*
-- 
2.20.1