[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>

2 files changed, 13 insertions, 2 deletions

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 @@ gotten:
 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 @@ retry:
 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