On Thu, 2007-06-14 at 16:58 +0400, Oleg Nesterov wrote: > > > Well, the only code path in which we'd want to call cancel_freezing() for > > kernel > > threads is when the freezing of kernel threads. However, this only happens > > if > > one of the kernel threads declares itself as freezable and the fails to call > > try_to_freeze(), which is a bug. > > But this happens? We know a lot of reasons why try_to_freeze() can fail just > because some kthread waits for already frozen task.
The freezer is a deadlock-o-matic by design. It's one of the major if not the main reason why we don't use the code in kernel/power.c on PowerBooks for suspend-to-ram. I don't like it and paulus hates it. > Well, we can have very subtle problems because a kernel thread may run with > TIF_SIGPENDING forever. This means in particualar that any > wait_event_interruptible() > can't succeed. I think this is worse than explicit failure (like > -ERESSTART... leak), > because it is hard to reproduce/debug. Then just don't send signals to them... > > Moreover, I'm not sure that it's a good idea at all to send signals to > > kernel > > threads from the freezer, since in fact we only need to wake them up to make > > them call try_to_freeze() (after we've set TIF_FREEZE for them). > > Yes! I completely agree. Sounds like a plan... Freezer problem 1/102893264 solved. Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
