Re: FAILED: patch "[PATCH] thp: use is_zero_pfn() only after pte_present() check" failed to apply to 4.2-stable tree

[Minchan Kim <minchan@kernel.org>]

Hi Greg,

On Thu, Nov 05, 2015 at 04:29:48PM -0800, gregkh@linuxfoundation.org wrote:
> 
> The patch below does not apply to the 4.2-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 <stable@vger.kernel.org>.

This is backport patch for v4.2.5.
If something is wrong(e.g. process, description and so on),
let me know it.

Thanks.

>From 6db5ccd1e927fc1181ea849ca73f089608071ed9 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Fri, 6 Nov 2015 11:11:08 +0900
Subject: [PATCH] thp: use is_zero_pfn() only after pte_present() check

This is backport for v4.2.5
Original commit id is 47aee4d8e314384807e98b67ade07f6da476aa75

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 mm/huge_memory.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 097c7a4..da0ac6a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2132,7 +2132,8 @@ static int __collapse_huge_page_isolate(struct vm_area_struct *vma,
 	for (_pte = pte; _pte < pte+HPAGE_PMD_NR;
 	     _pte++, address += PAGE_SIZE) {
 		pte_t pteval = *_pte;
-		if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
+		if (pte_none(pteval) || (pte_present(pteval) &&
+			is_zero_pfn(pte_pfn(pteval)))) {
 			if (++none_or_zero <= khugepaged_max_ptes_none)
 				continue;
 			else
-- 
1.9.1