From f44d21985eb6af7361d3785e26923355172147bd Mon Sep 17 00:00:00 2001
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Date: Wed, 21 Mar 2012 16:33:56 -0700
Subject: mm: do not reset cached_hole_size when vma is unmapped

In the current code, cached_hole_size is set to the maximum value if the
unmapped vma is less that free_area_cache so the next search will search
from the base address.

Actually, we can keep cached_hole_size so that if the next required size
is more than cached_hole_size, it can search from free_area_cache.

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mmap.c b/mm/mmap.c
index da15a79..4f31764 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1426,10 +1426,8 @@ void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
 	/*
 	 * Is this a new hole at the lowest possible address?
 	 */
-	if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
+	if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache)
 		mm->free_area_cache = addr;
-		mm->cached_hole_size = ~0UL;
-	}
 }
 
 /*
-- 
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