From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Date: Mon, 12 Dec 2011 23:40:34 +0000 (+0100)
Subject: export __get_user_pages_fast() function
X-Git-Tag: v2.6.32.51~5
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=1872856ac3ed878ec621a02573cff56491d9f410;p=linux-pvops.git

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>
---

diff --git a/mm/util.c b/mm/util.c
index b377ce430803..e48b493d40f8 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -233,6 +233,19 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 }
 #endif
 
+/*
+ * 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);
+
 /**
  * get_user_pages_fast() - pin user pages in memory
  * @start:	starting user address