Commits
Peter Zijlstra (Intel) committed 8f95b435b62
perf: Fix move_group() order Jiri reported triggering the new WARN_ON_ONCE in event_sched_out over the weekend: event_sched_out.isra.79+0x2b9/0x2d0 group_sched_out+0x69/0xc0 ctx_sched_out+0x106/0x130 task_ctx_sched_out+0x37/0x70 __perf_install_in_context+0x70/0x1a0 remote_function+0x48/0x60 generic_exec_single+0x15b/0x1d0 smp_call_function_single+0x67/0xa0 task_function_call+0x53/0x80 perf_install_in_context+0x8b/0x110 I think the below should cure this; if we install a group leader it will iterate the (still intact) group list and find its siblings and try and install those too -- even though those still have the old event->ctx -- in the new ctx. Upon installing the first group sibling we'd try and schedule out the group and trigger the above warn. Fix this by installing the group leader last, installing siblings would have no effect, they're not reachable through the group lists and therefore we don't schedule them. Also delay resetting the state until we're absolutely sure the events are quiescent. Reported-by: Jiri Olsa <jolsa@redhat.com> Reported-by: vincent.weaver@maine.edu Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/20150126162639.GA21418@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org>