From: Weijie Yang <weijie.yang@samsung.com>
Date: Tue, 7 Apr 2015 23:44:39 +0000 (+1000)
Subject: mm: page_isolation: check pfn validity before access
X-Git-Tag: KARO-TXA5-2015-06-26~18^2~253
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=76bd51df29c44e2d405633d489bcd73a9081a29f;p=karo-tx-linux.git

mm: page_isolation: check pfn validity before access

In the undo path of start_isolate_page_range(), we need to check the pfn
validity before accessing its page, or it will trigger an addressing
exception if there is hole in the zone.

This issue is found by code-review not a test-trigger.  In
"CONFIG_HOLES_IN_ZONE" environment, there is a certain chance that it
would casue an addressing exception when start_isolate_page_range()
fails, this could affect CMA, hugepage and memory-hotplug function.

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 755a42c76eb4..0c4505be0ed6 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -177,8 +177,11 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 undo:
 	for (pfn = start_pfn;
 	     pfn < undo_pfn;
-	     pfn += pageblock_nr_pages)
-		unset_migratetype_isolate(pfn_to_page(pfn), migratetype);
+	     pfn += pageblock_nr_pages) {
+		page = __first_valid_page(pfn, pageblock_nr_pages);
+		if (page)
+			unset_migratetype_isolate(page, migratetype);
+	}
 
 	return -EBUSY;
 }