From 85facf2570698ca6082326df4d63edebc9c9d96e Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Mon, 4 Feb 2013 14:28:42 -0800
Subject: [PATCH] thp: avoid dumping huge zero page

No reason to preserve the huge zero page in core dumps.

Reported-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/huge_memory.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6001ee6347a9..b5783d81eda9 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1257,6 +1257,10 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
 	if (flags & FOLL_WRITE && !pmd_write(*pmd))
 		goto out;
 
+	/* Avoid dumping huge zero page */
+	if ((flags & FOLL_DUMP) && is_huge_zero_pmd(*pmd))
+		return ERR_PTR(-EFAULT);
+
 	page = pmd_page(*pmd);
 	VM_BUG_ON(!PageHead(page));
 	if (flags & FOLL_TOUCH) {
-- 
2.20.1