[RFC][PATCH 2/2] throttle writers of shared mappings

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

From: Peter Zijlstra <a.p.zijlstra@chello.nl>

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>

---

 mm/memory.c |    7 +++++++
 1 file changed, 7 insertions(+)

Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c	2006-05-08 18:20:49.000000000 +0200
+++ linux-2.6/mm/memory.c	2006-05-08 18:35:26.000000000 +0200
@@ -50,6 +50,7 @@
 #include <linux/init.h>
 #include <linux/mm_page_replace.h>
 #include <linux/backing-dev.h>
+#include <linux/writeback.h>
 
 #include <asm/pgalloc.h>
 #include <asm/uaccess.h>
@@ -2183,8 +2184,11 @@ retry:
 unlock:
 	pte_unmap_unlock(page_table, ptl);
 	if (dirty) {
+		struct address_space *mapping = page_mapping(new_page);
 		set_page_dirty(new_page);
 		put_page(new_page);
+		if (mapping)
+			balance_dirty_pages_ratelimited_nr(mapping, 1);
 	}
 	return ret;
 oom:
@@ -2304,8 +2308,11 @@ static inline int handle_pte_fault(struc
 unlock:
 	pte_unmap_unlock(pte, ptl);
 	if (page) {
+		struct address_space *mapping = page_mapping(page);
 		set_page_dirty(page);
 		put_page(page);
+		if (mapping)
+			balance_dirty_pages_ratelimited_nr(mapping, 1);
 	}
 	return VM_FAULT_MINOR;
 }


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