x86: trim mtrr don't close gap for resource allocation.

fix the bug reported here:

	http://bugzilla.kernel.org/show_bug.cgi?id=10232

use update_memory_range() instead of add_memory_range() directly
to avoid closing the gap.

( the new code only affects and runs on systems where the MTRR
  workaround triggers. )

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

3 files changed, 55 insertions, 1 deletions

diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
index be83336fddba..a6450b3ae759 100644
--- a/arch/x86/kernel/cpu/mtrr/main.c
+++ b/arch/x86/kernel/cpu/mtrr/main.c
@@ -711,7 +711,8 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
                 trim_size = end_pfn;
                 trim_size <<= PAGE_SHIFT;
                 trim_size -= trim_start;
-                add_memory_region(trim_start, trim_size, E820_RESERVED);
+                update_memory_range(trim_start, trim_size, E820_RAM,
+                                        E820_RESERVED);
                 update_e820();
                 return 1;
         }
diff --git a/arch/x86/kernel/e820_32.c b/arch/x86/kernel/e820_32.c
index 4e16ef4a2659..80444c5c9b14 100644
--- a/arch/x86/kernel/e820_32.c
+++ b/arch/x86/kernel/e820_32.c
@@ -749,6 +749,32 @@ static int __init parse_memmap(char *arg)
         return 0;
 }
 early_param("memmap", parse_memmap);
+void __init update_memory_range(u64 start, u64 size, unsigned old_type,
+                                unsigned new_type)
+{
+        int i;
+
+        BUG_ON(old_type == new_type);
+
+        for (i = 0; i < e820.nr_map; i++) {
+                struct e820entry *ei = &e820.map[i];
+                u64 final_start, final_end;
+                if (ei->type != old_type)
+                        continue;
+                /* totally covered? */
+                if (ei->addr >= start && ei->size <= size) {
+                        ei->type = new_type;
+                        continue;
+                }
+                /* partially covered */
+                final_start = max(start, ei->addr);
+                final_end = min(start + size, ei->addr + ei->size);
+                if (final_start >= final_end)
+                        continue;
+                add_memory_region(final_start, final_end - final_start,
+                                         new_type);
+        }
+}
 void __init update_e820(void)
 {
         u8 nr_map;
diff --git a/arch/x86/kernel/e820_64.c b/arch/x86/kernel/e820_64.c
index 9f65b4cc323c..9be697126013 100644
--- a/arch/x86/kernel/e820_64.c
+++ b/arch/x86/kernel/e820_64.c
@@ -744,6 +744,33 @@ void __init finish_e820_parsing(void)
         }
 }
 
+void __init update_memory_range(u64 start, u64 size, unsigned old_type,
+                                unsigned new_type)
+{
+        int i;
+
+        BUG_ON(old_type == new_type);
+
+        for (i = 0; i < e820.nr_map; i++) {
+                struct e820entry *ei = &e820.map[i];
+                u64 final_start, final_end;
+                if (ei->type != old_type)
+                        continue;
+                /* totally covered? */
+                if (ei->addr >= start && ei->size <= size) {
+                        ei->type = new_type;
+                        continue;
+                }
+                /* partially covered */
+                final_start = max(start, ei->addr);
+                final_end = min(start + size, ei->addr + ei->size);
+                if (final_start >= final_end)
+                        continue;
+                add_memory_region(final_start, final_end - final_start,
+                                         new_type);
+        }
+}
+
 void __init update_e820(void)
 {
         u8 nr_map;