export __get_user_pages_fast() function

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@suse.de>
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/mm/util.c b/mm/util.c
index cb00b748ce47886446975d96466c2154f4d52fa3..434f9257ed69ed4a4c574b9d0eb138c64ea7795c 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -101,6 +101,19 @@ void *__krealloc(const void *p, size_t new_size, gfp_t flags)
 }
 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.