[PATCH 63/91] export __get_user_pages_fast() function

[Willy Tarreau]

2.6.27-longterm review patch.  If anyone has any objections, please let us know.

------------------

commit 45888a0c6edc305495b6bd72a30e66bc40b324c6 upstream.

Backport for stable kernel v2.6.32.y to v2.6.36.y.

Needed for next patch:

 oprofile, x86: Fix nmi-unsafe callgraph support

This function is used by KVM to pin process's page in the atomic context.

Define the 'weak' function to avoid other architecture not support it

Acked-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Robert Richter <robert.richter@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 mm/util.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

Index: longterm-2.6.27/mm/util.c
===================================================================
--- longterm-2.6.27.orig/mm/util.c	2012-02-05 22:34:33.070915063 +0100
+++ longterm-2.6.27/mm/util.c	2012-02-05 22:34:43.848914804 +0100
@@ -101,6 +101,19 @@
 }
 EXPORT_SYMBOL(__krealloc);
 
+/*
+ * Like get_user_pages_fast() except its IRQ-safe in that it won't fall
+ * back to the regular GUP.
+ * If the architecture not support this fucntion, simply return with no
+ * page pinned
+ */
+int __attribute__((weak)) __get_user_pages_fast(unsigned long start,
+				 int nr_pages, int write, struct page **pages)
+{
+	return 0;
+}
+EXPORT_SYMBOL_GPL(__get_user_pages_fast);
+
 /**
  * krealloc - reallocate memory. The contents will remain unchanged.
  * @p: object to reallocate memory for.


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