From 9a0f05cb36888550d1509d60aa55788615abea44 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Mon, 21 Nov 2011 15:13:29 +0100
Subject: [PATCH] perf: Update the mmap control page on mmap()

Apparently we didn't update the mmap control page right after mmap(),
which leads to surprises when userspace wants to use it.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arun Sharma <asharma@fb.com>
Link: http://lkml.kernel.org/n/tip-dcpi7164djsexmx6ya7lilrc@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/events/core.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 2f8f3f103cb4..0ca1f648ac08 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3534,6 +3534,8 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	event->mmap_user = get_current_user();
 	vma->vm_mm->pinned_vm += event->mmap_locked;
 
+	perf_event_update_userpage(event);
+
 unlock:
 	if (!ret)
 		atomic_inc(&event->mmap_count);