Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fix from Ingo Molnar:
 "A single fix to not allow nonsensical event groups that result in
  kernel warnings"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix group {cpu,task} validation

1 files changed, 19 insertions, 20 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index ee20d4c546b5..3504125871d2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10032,28 +10032,27 @@ SYSCALL_DEFINE5(perf_event_open,
                         goto err_context;
 
                 /*
-                 * Do not allow to attach to a group in a different
-                 * task or CPU context:
+                 * Make sure we're both events for the same CPU;
+                 * grouping events for different CPUs is broken; since
+                 * you can never concurrently schedule them anyhow.
                  */
-                if (move_group) {
-                        /*
-                         * Make sure we're both on the same task, or both
-                         * per-cpu events.
-                         */
-                        if (group_leader->ctx->task != ctx->task)
-                                goto err_context;
+                if (group_leader->cpu != event->cpu)
+                        goto err_context;
 
-                        /*
-                         * Make sure we're both events for the same CPU;
-                         * grouping events for different CPUs is broken; since
-                         * you can never concurrently schedule them anyhow.
-                         */
-                        if (group_leader->cpu != event->cpu)
-                                goto err_context;
-                } else {
-                        if (group_leader->ctx != ctx)
-                                goto err_context;
-                }
+                /*
+                 * Make sure we're both on the same task, or both
+                 * per-CPU events.
+                 */
+                if (group_leader->ctx->task != ctx->task)
+                        goto err_context;
+
+                /*
+                 * Do not allow to attach to a group in a different task
+                 * or CPU context. If we're moving SW events, we'll fix
+                 * this up later, so allow that.
+                 */
+                if (!move_group && group_leader->ctx != ctx)
+                        goto err_context;
 
                 /*
                  * Only a group leader can be exclusive or pinned