The current posix-cpu-timer code uses pids when holding persistent references in timers. However the lookups from clockid_t still return tasks that need to be converted into pids for use.
This results in usage being pid->task->pid and that can race with release_task and de_thread. This can lead to some not wrong but surprising results. Surprising enough that Oleg and I both thought there were some bugs in the code for a while. This set of changes modifies the code to just lookup, verify, and return pids from the clockid_t lookups to remove those potentialy troublesome races. Eric W. Biederman (3): posix-cpu-timers: Extend rcu_read_lock removing task_struct references posix-cpu-timers: Replace cpu_timer_pid_type with clock_pid_type posix-cpu-timers: Replace __get_task_for_clock with pid_for_clock kernel/time/posix-cpu-timers.c | 102 ++++++++++++++++++----------------------- 1 file changed, 45 insertions(+), 57 deletions(-) Suggested-by: Oleg Nesterov <o...@redhat.com> Signed-off-by: "Eric W. Biederman" <ebied...@xmission.com> --- The changes can also be found here: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git proc-testing