perf: Fix mmap() accounting hole
Vince's fuzzer once again found holes. This time it spotted a leak in
the locked page accounting.
When an event had redirected output and its close() was the last
reference to the buffer we didn't have a vm context to undo accounting.
Change the code to destroy the buffer on the last munmap() and detach
all redirected events at that time. This provides us the right context
to undo the vm accounting.
Reported-and-tested-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130604084421.GI8923@twins.programming.kicks-ass.net
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/events/internal.h b/kernel/events/internal.h
index 5bc6c8e..ca65997 100644
--- a/kernel/events/internal.h
+++ b/kernel/events/internal.h
@@ -31,7 +31,8 @@
spinlock_t event_lock;
struct list_head event_list;
- int mmap_locked;
+ atomic_t mmap_count;
+ unsigned long mmap_locked;
struct user_struct *mmap_user;
struct perf_event_mmap_page *user_page;