linux-kernel - [RFC PATCH 3/3] mm, page_alloc: prevent merge freepages between highatomic and others

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 for Android: free password hash cracker in your pocket

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

Date:	Sun, 19 Jun 2016 09:51:43 +0800
From:	Wenwei Tao <wwtao0320@....com>
To:	akpm@...ux-foundation.org, mgorman@...hsingularity.net
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	ww.tao0320@...il.com
Subject: [RFC PATCH 3/3] mm, page_alloc: prevent merge freepages between highatomic and others

From: Wenwei Tao <ww.tao0320@...il.com>

We might not want other migrate types pin highatomic pageblock
away since it's reserved for high order use. And also we might
not want reserve high atomic pages out of limit, we can add
check in __free_one_page but this might be costly, so just stop
the merging.

Signed-off-by: Wenwei Tao <ww.tao0320@...il.com>
---
 mm/page_alloc.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b72b771..ffce9b5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -832,7 +832,8 @@ continue_merging:
 		 * We don't want to hit this code for the more frequent
 		 * low-order merging.
 		 */
-		if (unlikely(has_isolate_pageblock(zone))) {
+		if (unlikely(has_isolate_pageblock(zone) ||
+				zone->nr_reserved_highatomic)) {
 			int buddy_mt;
 
 			buddy_idx = __find_buddy_index(page_idx, order);
@@ -841,7 +842,9 @@ continue_merging:
 
 			if (migratetype != buddy_mt
 					&& (is_migrate_isolate(migratetype) ||
-						is_migrate_isolate(buddy_mt)))
+					is_migrate_isolate(buddy_mt) ||
+					migratetype == MIGRATE_HIGHATOMIC ||
+					buddy_mt == MIGRATE_HIGHATOMIC))
 				goto done_merging;
 		}
 		max_order++;
-- 
1.8.3.1