linux-kernel - [PATCH] mem-hotplug: improve zone_movable_is

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>] [day] [month] [year] [list]

Date:	Fri, 20 Jun 2014 18:54:14 +0800
From:	Wang Nan <wangnan0@...wei.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>, Jiang Liu <liuj97@...il.com>
CC:	<linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
	Wang Nan <wangnan0@...wei.com>, Li Zefan <lizefan@...wei.com>
Subject: [PATCH] mem-hotplug: improve zone_movable_is_highmem logic

In original code, zone_movable_is_highmem() assumes ZONE_MOVABLE not
highmem if CONFIG_HAVE_MEMBLOCK_NODE_MAP is not set. In online_pages, it
extracts pages from the previous zone before ZONE_MOVABLE. Which is
logically inconsistent:

If HAVE_MEMBLOCK_NODE_MAP is turned off but HIGHMEM is on,
zone_movable_is_highmem() makes movable zone not highmem, but
online_pages() extracts pages from ZONE_HIGHMEM.

This inconsistency doesn't cause real problem currently, because all
architectures support online_pages also have HAVE_MEMBLOCK_NODE_MAP.
However, fixing it makes code clear, and also helps futher coding.

Signed-off-by: Wang Nan <wangnan0@...wei.com>
Cc: Zhang Zhen <zhangzhen@...wei.com>
---
 include/linux/mmzone.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6cbd1b6..559e659 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -872,6 +872,8 @@ static inline int zone_movable_is_highmem(void)
 {
 #if defined(CONFIG_HIGHMEM) && defined(CONFIG_HAVE_MEMBLOCK_NODE_MAP)
 	return movable_zone == ZONE_HIGHMEM;
+#elif defined(CONFIG_HIGHMEM)
+	return (ZONE_MOVABLE - 1) == ZONE_HIGHMEM;
 #else
 	return 0;
 #endif
-- 
1.8.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/