FAILED: patch "[PATCH] mm/pagewalk.c: report holes in hugetlb ranges" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Jann Horn <[email protected]>
Date: Tue, 14 Nov 2017 01:03:44 +0100
Subject: [PATCH] mm/pagewalk.c: report holes in hugetlb ranges

This matters at least for the mincore syscall, which will otherwise copy uninitialized memory from the page allocator to userspace. It is probably also a correctness error for /proc/$pid/pagemap, but I haven't tested that.

Removing the walk->hugetlb_entry condition in walk_hugetlb_range() has no effect because the caller already checks for that.

This only reports holes in hugetlb ranges to callers who have specified a hugetlb_entry callback.

This issue was found using an AFL-based fuzzer.

v2:
- don't crash on ->pte_hole==NULL (Andrew Morton)
- add Cc stable (Andrew Morton)

index 8bd4afa83cb8..23a3e415ac2c 100644
@@ -188,8 +188,12 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 	do {
 		next = hugetlb_entry_end(h, addr, end);
 		pte = huge_pte_offset(walk->mm, addr & hmask, sz);
-		if (pte && walk->hugetlb_entry)
+
+		if (pte)
 			err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
+		else if (walk->pte_hole)
+			err = walk->pte_hole(addr, next, walk);
+
 		if (err)
 			break;
 	} while (addr = next, addr != end);