[PATCH] memory hotplug: update the variables after memory removed

[Zhang Zhen]

Commit ea0854170c95245a258b386c7a9314399c949fe0 added a fuction
update_end_of_memory_vars() to update high_memory, max_pfn and
max_low_pfn.

Here modified the function(added an argument to show add or remove).
And call it in arch_remove_memory() to update these variables too.

Signed-off-by: Zhang Zhen <zhenzhang.zh...@huawei.com>
---
 arch/x86/mm/init_64.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index df1a992..2557091 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -673,14 +673,24 @@ void __init paging_init(void)
  * After memory hotplug the variables max_pfn, max_low_pfn and high_memory need
  * updating.
  */
-static void  update_end_of_memory_vars(u64 start, u64 size)
+static void  update_end_of_memory_vars(u64 start, u64 size, bool flag)
 {
-       unsigned long end_pfn = PFN_UP(start + size);
-
-       if (end_pfn > max_pfn) {
-               max_pfn = end_pfn;
-               max_low_pfn = end_pfn;
-               high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+       unsigned long end_pfn;
+
+       if (flag) {
+               end_pfn = PFN_UP(start + size);
+               if (end_pfn > max_pfn) {
+                       max_pfn = end_pfn;
+                       max_low_pfn = end_pfn;
+                       high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+               }
+       } else {
+               end_pfn = PFN_UP(start);
+               if (end_pfn < max_pfn) {
+                       max_pfn = end_pfn;
+                       max_low_pfn = end_pfn;
+                       high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+               }
        }
 }

@@ -702,7 +712,7 @@ int arch_add_memory(int nid, u64 start, u64 size)
        WARN_ON_ONCE(ret);

        /* update max_pfn, max_low_pfn and high_memory */
-       update_end_of_memory_vars(start, size);
+       update_end_of_memory_vars(start, size, true);

        return ret;
 }
@@ -1025,6 +1035,9 @@ int __ref arch_remove_memory(u64 start, u64 size)
        ret = __remove_pages(zone, start_pfn, nr_pages);
        WARN_ON_ONCE(ret);

+       /* update max_pfn, max_low_pfn and high_memory */
+       update_end_of_memory_vars(start, size, false);
+
        return ret;
 }
 #endif
-- 
1.8.1.2


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