linux-kernel - [PATCH v4 8/8] mm: rmap: Use correct helper when poisoning hugepages

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Message-Id: <20170524115409.31309-9-punit.agrawal@arm.com>
Date:   Wed, 24 May 2017 12:54:09 +0100
From:   Punit Agrawal <punit.agrawal@....com>
To:     akpm@...ux-foundation.org
Cc:     Punit Agrawal <punit.agrawal@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        catalin.marinas@....com, will.deacon@....com,
        n-horiguchi@...jp.nec.com, kirill.shutemov@...ux.intel.com,
        mike.kravetz@...cle.com, steve.capper@....com,
        mark.rutland@....com, linux-arch@...r.kernel.org,
        aneesh.kumar@...ux.vnet.ibm.com
Subject: [PATCH v4 8/8] mm: rmap: Use correct helper when poisoning hugepages

Using set_pte_at() does not do the right thing when putting down
HWPOISON swap entries for hugepages on architectures that support
contiguous ptes.

Fix this problem by using set_huge_swap_pte_at() which was introduced to
fix exactly this problem.

Signed-off-by: Punit Agrawal <punit.agrawal@....com>
Acked-by: Steve Capper <steve.capper@....com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
---
 mm/rmap.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index d405f0e0ee96..feb2352aa95f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1379,15 +1379,18 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		update_hiwater_rss(mm);
 
 		if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
+			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
 			if (PageHuge(page)) {
 				int nr = 1 << compound_order(page);
 				hugetlb_count_sub(nr, mm);
+				set_huge_swap_pte_at(mm, address,
+						     pvmw.pte, pteval,
+						     vma_mmu_pagesize(vma));
 			} else {
 				dec_mm_counter(mm, mm_counter(page));
+				set_pte_at(mm, address, pvmw.pte, pteval);
 			}
 
-			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
-			set_pte_at(mm, address, pvmw.pte, pteval);
 		} else if (pte_unused(pteval)) {
 			/*
 			 * The guest indicated that the page content is of no
-- 
2.11.0