From: Paul Szabo <psz@maths.usyd.edu.au>
Date: Thu, 7 Feb 2013 01:26:53 +0000 (+1100)
Subject: page-writeback.c: subtract min_free_kbytes from dirtyable memory
X-Git-Tag: next-20130218~1^2~370
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=1ecdcdf5821684c2df737cf668e41fc41cacd32d;p=karo-tx-linux.git

page-writeback.c: subtract min_free_kbytes from dirtyable memory

When calculating amount of dirtyable memory, min_free_kbytes should be
subtracted because it is not intended for dirty pages.

Addresses http://bugs.debian.org/695182

Signed-off-by: Paul Szabo <psz@maths.usyd.edu.au>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index cefafebe4cbc..79530ec50cbd 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -234,6 +234,7 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
 static unsigned long global_dirtyable_memory(void)
 {
 	unsigned long x;
+	extern int min_free_kbytes;
 
 	x = global_page_state(NR_FREE_PAGES) + global_reclaimable_pages();
 	x -= min(x, dirty_balance_reserve);
@@ -241,6 +242,9 @@ static unsigned long global_dirtyable_memory(void)
 	if (!vm_highmem_is_dirtyable)
 		x -= highmem_dirtyable_memory(x);
 
+	/* Subtract min_free_kbytes */
+	x -= min(x, min_free_kbytes >> (PAGE_SHIFT - 10));
+
 	return x + 1;	/* Ensure that we never return 0 */
 }