From: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Date: Wed, 19 Jun 2013 00:06:13 +0000 (+1000)
Subject: mm/memory-hotplug: fix lowmem count overflow when offline pages
X-Git-Tag: next-20130619~2^2~490
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f3613fc3019a869b7b20e187ca8bc00b35ec8ff6;p=karo-tx-linux.git

mm/memory-hotplug: fix lowmem count overflow when offline pages

Logic memory-remove code fails to correctly account the Total High Memory
when a memory block which contains High Memory is offlined as shown in the
example below.  The following patch fixes it.

Before logic memory remove:

MemTotal:        7603740 kB
MemFree:         6329612 kB
Buffers:           94352 kB
Cached:           872008 kB
SwapCached:            0 kB
Active:           626932 kB
Inactive:         519216 kB
Active(anon):     180776 kB
Inactive(anon):   222944 kB
Active(file):     446156 kB
Inactive(file):   296272 kB
Unevictable:           0 kB
Mlocked:               0 kB
HighTotal:       7294672 kB
HighFree:        5704696 kB
LowTotal:         309068 kB
LowFree:          624916 kB

After logic memory remove:

MemTotal:        7079452 kB
MemFree:         5805976 kB
Buffers:           94372 kB
Cached:           872000 kB
SwapCached:            0 kB
Active:           626936 kB
Inactive:         519236 kB
Active(anon):     180780 kB
Inactive(anon):   222944 kB
Active(file):     446156 kB
Inactive(file):   296292 kB
Unevictable:           0 kB
Mlocked:               0 kB
HighTotal:       7294672 kB
HighFree:        5181024 kB
LowTotal:       4294752076 kB
LowFree:          624952 kB

Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: <stable@vger.kernel.org>	[2.6.24+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a662c74a0f5d..6f623f6d5c84 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6185,6 +6185,8 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 		list_del(&page->lru);
 		rmv_page_order(page);
 		zone->free_area[order].nr_free--;
+		if (PageHighMem(page))
+			totalhigh_pages -= 1 << order;
 		for (i = 0; i < (1 << order); i++)
 			SetPageReserved((page+i));
 		pfn += (1 << order);