Messages in this thread | | | Date | Mon, 31 Oct 2011 16:30:59 -0700 | From | Tejun Heo <> | Subject | Re: [RFC PATCH] freezer: revert 27920651fe "PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too" |
| |
Hello,
On Tue, Nov 01, 2011 at 12:24:16AM +0100, Rafael J. Wysocki wrote: > > This is probably okay for most cases but circumventing fundamental > > wakeup condition like this is asking for trouble. Furthermore, I'm > > not sure the behavior change brought on by this change - breaking > > nfs/cifs uninterruptible operation guarantee - is correct. If such > > behavior is desirable, the right thing to do is using intr mount > > option, not circumventing it from PM layer. > > Do you have any specific examples of breakage, or is it just that you _think_ > it's not quite right?
I can't remember one off the top of my head but I'm pretty sure there at least are few which expect tight inter-locking between sleeps and wakeups. I'll look for examples and post reply. ISTR them being kernel threads so this might not apply directly but it's still a dangerous game to play.
Bugs caused by behaviors like this will be very difficult to reproduce and diagnose. There is no reason to play a gamble like this. If somebody *really* wants non-interruptible killable & freezable sleep, we really should be adding TASK_WAKE_FREEZER or something instead of modifying the behavior of TASK_KILLABLE.
Thanks.
-- tejun
| |