From d5022d379a04f0bc02e7de4e54552cd38cdfce5a Mon Sep 17 00:00:00 2001
From: Wen Congyang <wency@cn.fujitsu.com>
Date: Thu, 25 Oct 2012 12:14:50 +1100
Subject: [PATCH] memory-hotplug: update mce_bad_pages when removing the memory

When we hotremove a memory device, we will free the memory to store struct
page.  If the page is hwpoisoned page, we should decrease mce_bad_pages.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/sparse.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/mm/sparse.c b/mm/sparse.c
index fac95f2888f2..24072e435bf8 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -773,6 +773,23 @@ out:
 	return ret;
 }
 
+#ifdef CONFIG_MEMORY_FAILURE
+static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+	int i;
+
+	if (!memmap)
+		return;
+
+	for (i = 0; i < PAGES_PER_SECTION; i++) {
+		if (PageHWPoison(&memmap[i])) {
+			atomic_long_sub(1, &mce_bad_pages);
+			ClearPageHWPoison(&memmap[i]);
+		}
+	}
+}
+#endif
+
 void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 {
 	struct page *memmap = NULL;
@@ -786,6 +803,10 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
 		ms->pageblock_flags = NULL;
 	}
 
+#ifdef CONFIG_MEMORY_FAILURE
+	clear_hwpoisoned_pages(memmap, PAGES_PER_SECTION);
+#endif
+
 	free_section_usemap(memmap, usemap);
 }
 #endif
-- 
2.39.5