[PATCH] [4/16] POISON: Export some rmap vma locking to outside world

[Andi Kleen <andi@firstfloor.org>]

Needed for later patch that walks rmap entries on its own.

This used to be very frowned upon, but memory-failure.c does
some rather specialized rmap walking and rmap has been stable
for quite some time, so I think it's ok now to export it.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
 include/linux/rmap.h |    6 ++++++
 mm/rmap.c            |    4 ++--
 2 files changed, 8 insertions(+), 2 deletions(-)

Index: linux/include/linux/rmap.h
===================================================================
--- linux.orig/include/linux/rmap.h	2009-04-07 16:39:26.000000000 +0200
+++ linux/include/linux/rmap.h	2009-04-07 16:43:06.000000000 +0200
@@ -118,6 +118,12 @@
 }
 #endif
 
+/*
+ * Called by memory-failure.c to kill processes.
+ */
+struct anon_vma *page_lock_anon_vma(struct page *page);
+void page_unlock_anon_vma(struct anon_vma *anon_vma);
+
 #else	/* !CONFIG_MMU */
 
 #define anon_vma_init()		do {} while (0)
Index: linux/mm/rmap.c
===================================================================
--- linux.orig/mm/rmap.c	2009-04-07 16:39:26.000000000 +0200
+++ linux/mm/rmap.c	2009-04-07 16:43:06.000000000 +0200
@@ -191,7 +191,7 @@
  * Getting a lock on a stable anon_vma from a page off the LRU is
  * tricky: page_lock_anon_vma rely on RCU to guard against the races.
  */
-static struct anon_vma *page_lock_anon_vma(struct page *page)
+struct anon_vma *page_lock_anon_vma(struct page *page)
 {
 	struct anon_vma *anon_vma;
 	unsigned long anon_mapping;
@@ -211,7 +211,7 @@
 	return NULL;
 }
 
-static void page_unlock_anon_vma(struct anon_vma *anon_vma)
+void page_unlock_anon_vma(struct anon_vma *anon_vma)
 {
 	spin_unlock(&anon_vma->lock);
 	rcu_read_unlock();