On 10/25, Tejun Heo wrote: > > Hello, Oleg. > > On Thu, Oct 25, 2012 at 06:39:59PM +0200, Oleg Nesterov wrote: > > Change ptrace_stop() and do_signal_stop() to use freezable_schedule() > > rather than rely on subsequent try_to_freeze(). > > > > This allows to remove the task_is_stopped_or_traced() checks from > > try_to_freeze_tasks() and update_if_frozen(), and this fixes the > > unlikely race with ptrace_stop(). If the tracee does not schedule() > > it can miss a freezing condition. > > I think it would be great if the description is more detailed. This > code path always makes my head spin and I think we can definitely use > some more guiding in understanding this dang thing. :) Do you mean describe the race in more details? OK, will do and resend tomorrow. > > @@ -2092,7 +2085,7 @@ static bool do_signal_stop(int signr) > > } > > > > /* Now we don't run again until woken by SIGCONT or SIGKILL */ > > - schedule(); > > + freezable_schedule(); > > This makes me wonder whether we still need try_to_freeze() in > get_signal_to_deliver() right after the relock: label. Freezer no > longer treats STOPPED/TRACED special and both sleeping sites in signal > deliver path are marked freezable_schedule(). We shouldn't need the > explicit try_to_freeze(), right? OOPS. I'd say this doesn't really matter but yes we can move it up, get_signal_to_deliver() will be called again. But! the comment above try_to_freeze() becomes misleading with this patch, so this really needs v2. Thanks. Oleg. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
