From edc79b2a46ed854595e40edcf3f8b37f9f14aa3f Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Mon, 25 Sep 2006 23:30:58 -0700
Subject: [PATCH] [PATCH] mm: balance dirty pages

Now that we can detect writers of shared mappings, throttle them.  Avoids OOM
by surprise.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 include/linux/writeback.h |  1 +
 mm/memory.c               |  5 +++--
 mm/page-writeback.c       | 10 ++++++++++
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 0422036af4eb..56a23a0e7f2e 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -116,6 +116,7 @@ int sync_page_range(struct inode *inode, struct address_space *mapping,
 			loff_t pos, loff_t count);
 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
 			   loff_t pos, loff_t count);
+void set_page_dirty_balance(struct page *page);
 
 /* pdflush.c */
 extern int nr_pdflush_threads;	/* Global so it can be exported to sysctl
diff --git a/mm/memory.c b/mm/memory.c
index fa941b169071..dd7d7fc5ed60 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -49,6 +49,7 @@
 #include <linux/module.h>
 #include <linux/delayacct.h>
 #include <linux/init.h>
+#include <linux/writeback.h>
 
 #include <asm/pgalloc.h>
 #include <asm/uaccess.h>
@@ -1571,7 +1572,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 unlock:
 	pte_unmap_unlock(page_table, ptl);
 	if (dirty_page) {
-		set_page_dirty(dirty_page);
+		set_page_dirty_balance(dirty_page);
 		put_page(dirty_page);
 	}
 	return ret;
@@ -2218,7 +2219,7 @@ static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
 unlock:
 	pte_unmap_unlock(page_table, ptl);
 	if (dirty_page) {
-		set_page_dirty(dirty_page);
+		set_page_dirty_balance(dirty_page);
 		put_page(dirty_page);
 	}
 	return ret;
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 1c87430b7a25..b9f4c6f1be86 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -244,6 +244,16 @@ static void balance_dirty_pages(struct address_space *mapping)
 		pdflush_operation(background_writeout, 0);
 }
 
+void set_page_dirty_balance(struct page *page)
+{
+	if (set_page_dirty(page)) {
+		struct address_space *mapping = page_mapping(page);
+
+		if (mapping)
+			balance_dirty_pages_ratelimited(mapping);
+	}
+}
+
 /**
  * balance_dirty_pages_ratelimited_nr - balance dirty memory state
  * @mapping: address_space which was dirtied
-- 
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