linux-kernel - [PATCH 4.8 081/125] mm/hugetlb: improve locking in dissolve_free_huge

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: <20161029134950.547900717@linuxfoundation.org>
Date:   Sat, 29 Oct 2016 09:49:59 -0400
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Gerald Schaefer <gerald.schaefer@...ibm.com>,
        Michal Hocko <mhocko@...e.com>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Rui Teng <rui.teng@...ux.vnet.ibm.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.8 081/125] mm/hugetlb: improve locking in dissolve_free_huge_pages()

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Gerald Schaefer <gerald.schaefer@...ibm.com>

commit eb03aa008561004257900983193d024e57abdd96 upstream.

For every pfn aligned to minimum_order, dissolve_free_huge_pages() will
call dissolve_free_huge_page() which takes the hugetlb spinlock, even if
the page is not huge at all or a hugepage that is in-use.

Improve this by doing the PageHuge() and page_count() checks already in
dissolve_free_huge_pages() before calling dissolve_free_huge_page().  In
dissolve_free_huge_page(), when holding the spinlock, those checks need
to be revalidated.

Link: http://lkml.kernel.org/r/20160926172811.94033-4-gerald.schaefer@de.ibm.com
Signed-off-by: Gerald Schaefer <gerald.schaefer@...ibm.com>
Acked-by: Michal Hocko <mhocko@...e.com>
Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Mike Kravetz <mike.kravetz@...cle.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@...ux.vnet.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@...ibm.com>
Cc: Heiko Carstens <heiko.carstens@...ibm.com>
Cc: Rui Teng <rui.teng@...ux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 mm/hugetlb.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1476,14 +1476,20 @@ out:
 int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
 {
 	unsigned long pfn;
+	struct page *page;
 	int rc = 0;

 	if (!hugepages_supported())
 		return rc;

-	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order)
-		if (rc = dissolve_free_huge_page(pfn_to_page(pfn)))
-			break;
+	for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << minimum_order) {
+		page = pfn_to_page(pfn);
+		if (PageHuge(page) && !page_count(page)) {
+			rc = dissolve_free_huge_page(page);
+			if (rc)
+				break;
+		}
+	}

 	return rc;
 }