[RFC][PATCH 1/6] perf: Update the mmap control page on mmap()

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

[-- Attachment #1: perf-fix-userpage.patch --]
[-- Type: text/plain, Size: 758 bytes --]

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

Cc: Stephane Eranian <eranian@google.com>
Cc: Arun Sharma <asharma@fb.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 kernel/events/core.c |    2 ++
 1 file changed, 2 insertions(+)
Index: linux-2.6/kernel/events/core.c
===================================================================
--- linux-2.6.orig/kernel/events/core.c
+++ linux-2.6/kernel/events/core.c
@@ -3463,6 +3463,8 @@ static int perf_mmap(struct file *file, 
 	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);