From 1a11e8d818c6099b9bcdf7b4a60a1f49b15454e1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue, 18 May 2010 10:33:24 +0200
Subject: [PATCH] --- yaml --- r: 199093 b: refs/heads/master c:
 c7920614cebbf269a7c8397ff959a8dcf727465c h: refs/heads/master i:   199091:
 b8e63aea320fa5f27742d27dc57f3e869a922e8f v: v3

---
 [refs]                    | 2 +-
 trunk/kernel/perf_event.c | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index dd563d866ba1..90fd90228874 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a19d35c11fd559dd7dfd5a2078df7c9af74a5d88
+refs/heads/master: c7920614cebbf269a7c8397ff959a8dcf727465c
diff --git a/trunk/kernel/perf_event.c b/trunk/kernel/perf_event.c
index 6ae62186dd0c..ff5d430d45a7 100644
--- a/trunk/kernel/perf_event.c
+++ b/trunk/kernel/perf_event.c
@@ -2593,6 +2593,14 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma)
 	long user_extra, extra;
 	int ret = 0;
 
+	/*
+	 * Don't allow mmap() of inherited per-task counters. This would
+	 * create a performance issue due to all children writing to the
+	 * same buffer.
+	 */
+	if (event->cpu == -1 && event->attr.inherit)
+		return -EINVAL;
+
 	if (!(vma->vm_flags & VM_SHARED))
 		return -EINVAL;