Changelog:
 v1 -> v2:
        * show number of HighTotal before hotremove 
        * remove CONFIG_HIGHMEM
        * cc stable kernels
        * add Michal reviewed-by

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.

Stable for 2.6.24+.

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

Reviewed-by: Michal Hocko <mho...@suse.cz>
Signed-off-by: Wanpeng Li <liw...@linux.vnet.ibm.com>
---
 mm/page_alloc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 98cbdf6..23b921f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6140,6 +6140,8 @@ __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);
-- 
1.8.1.2

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