linux-kernel - [PATCH 3/6] khugepaged: Drain all LRU caches before scanning pages

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]

Date:   Mon, 13 Apr 2020 13:04:44 +0300
From:   "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To:     akpm@...ux-foundation.org, Andrea Arcangeli <aarcange@...hat.com>
Cc:     Zi Yan <ziy@...dia.com>, Yang Shi <yang.shi@...ux.alibaba.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        John Hubbard <jhubbard@...dia.com>,
        William Kucharski <william.kucharski@...cle.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH 3/6] khugepaged: Drain all LRU caches before scanning pages

Having a page in LRU add cache offsets page refcount and gives
false-negative on PageLRU(). It reduces collapse success rate.

Drain all LRU add caches before scanning. It happens relatively
rare and should not disturb the system too much.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
 mm/khugepaged.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 5968ec5ddd6b..ee66c140c2d6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2059,6 +2059,8 @@ static void khugepaged_do_scan(void)
 
 	barrier(); /* write khugepaged_pages_to_scan to local stack */
 
+	lru_add_drain_all();
+
 	while (progress < pages) {
 		if (!khugepaged_prealloc_page(&hpage, &wait))
 			break;
-- 
2.26.0