linux-kernel - [PATCH v6 38/51] mm: Fix total_mapcount assumption of page size

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200610201345.13273-39-willy@infradead.org>
Date:   Wed, 10 Jun 2020 13:13:32 -0700
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     "Kirill A. Shutemov" <kirill@...temov.name>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Matthew Wilcox <willy@...radead.org>
Subject: [PATCH v6 38/51] mm: Fix total_mapcount assumption of page size

From: "Kirill A. Shutemov" <kirill@...temov.name>

File THPs may now be of arbitrary order.

Signed-off-by: Kirill A. Shutemov <kirill@...temov.name>
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 mm/huge_memory.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 80fb38e93837..744863aa0374 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2490,7 +2490,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
 
 int total_mapcount(struct page *page)
 {
-	int i, compound, ret;
+	int i, compound, nr, ret;
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
@@ -2498,16 +2498,17 @@ int total_mapcount(struct page *page)
 		return atomic_read(&page->_mapcount) + 1;
 
 	compound = compound_mapcount(page);
+	nr = compound_nr(page);
 	if (PageHuge(page))
 		return compound;
 	ret = compound;
-	for (i = 0; i < HPAGE_PMD_NR; i++)
+	for (i = 0; i < nr; i++)
 		ret += atomic_read(&page[i]._mapcount) + 1;
 	/* File pages has compound_mapcount included in _mapcount */
 	if (!PageAnon(page))
-		return ret - compound * HPAGE_PMD_NR;
+		return ret - compound * nr;
 	if (PageDoubleMap(page))
-		ret -= HPAGE_PMD_NR;
+		ret -= nr;
 	return ret;
 }
 
-- 
2.26.2