[ 3.8.y.z extended stable ] Patch "mm/memory-hotplug: fix lowmem count overflow when offline" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

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

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From f7210fe93206e57a3e72c043d43119428df5cba8 Mon Sep 17 00:00:00 2001
From: Wanpeng Li <liwanp at linux.vnet.ibm.com>
Date: Wed, 3 Jul 2013 15:02:40 -0700
Subject: [PATCH] mm/memory-hotplug: fix lowmem count overflow when offline
 pages

commit cea27eb2a202959783f81254c48c250ddd80e129 upstream.

The logic for the 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

[mhocko at suse.cz: fix CONFIG_HIGHMEM=n build]
Signed-off-by: Wanpeng Li <liwanp at linux.vnet.ibm.com>
Reviewed-by: Michal Hocko <mhocko at suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>
Cc: David Rientjes <rientjes at google.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 mm/page_alloc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7d77c57..7708f66 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6056,6 +6056,10 @@ __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--;
+#ifdef CONFIG_HIGHMEM
+		if (PageHighMem(page))
+			totalhigh_pages -= 1 << order;
+#endif
 		for (i = 0; i < (1 << order); i++)
 			SetPageReserved((page+i));
 		pfn += (1 << order);
--
1.8.1.2