On 03/07, Dmitry Vyukov wrote: > > On Tue, Mar 7, 2017 at 3:04 PM, Oleg Nesterov <o...@redhat.com> wrote: > > On 03/06, Peter Zijlstra wrote: > >> > >> and this is a failed fork(). > >> > >> > >> However, inherited events don't have a filedesc to fput(), and > >> similarly, a task that fails for has never been visible to attach a perf > >> event to because it never hits the pid-hash. > > > > Yes, it is not visible to find_task_by_vpid() until copy_process() does > > attach_pid(PIDTYPE_PID), and copy_process() can't fail after that. > > > I would what is that that is failed in copy_process. Could it be > perf_event_init_task itself? Maybe it leaves a pointer to p in some > shared state on some error conditions?
I am looking at perf_event_init_task() too and I can't understand the error handling... perf_event_init_context() can return success even if inherit_task_group() in the first list_for_each_entry(pinned_groups) fails, "ret" will be overwritten by the 2nd list_for_each_entry(flexible_groups) loop. "inherited_all" should be cleared, still this looks confusing at least. inherit_event() returns NULL under is_orphaned_event() check, not ERR_PTR(). Is it correct? Oleg.