On Mon, 3 Dec 2007 10:55:01 +0100 Andi Kleen wrote: > On Sun, Dec 02, 2007 at 04:59:13PM -0800, Arjan van de Ven wrote: > > On Mon, 3 Dec 2007 01:07:41 +0100 > > Andi Kleen wrote: > > > > > This patch will likely work against that by breaking error paths. > > > > it won't break error paths, it will at most put a warning in the log. > > It doesn't kill or otherwise damage the system or process. > > From the user perspective a kernel randomly throwing backtraces is > a broken kernel. Throwing in my 2c: Kernel waiting 2 minutes on TASK_UNINTERRUPTIBLE is certainly broken. I wouldn't wait that long for the system to become responsive, I yanked the power cord already. Hm, that's already detected with sleep_uninterruptible logic. A task that's not killable for more than 2 minutes is broken still, but less so. > > > > This patch is a step in the right direction there, by quite a > > > > lot. > > > > > > > > I really don't understand what your objection is to this patch... > > > > is it that an enterprise distro can't ship with it on? (Which is > > > > fine btw) > > > > > > Any distribution aimed at end users cannot ship with it on. > > > > That's a pretty bold statement; assuming that the TASK_KILLABLE patch > > is in, I don't see the problem. > > iirc TASK_KILLABLE fixed NFS only. While that's a good thing there are > unfortunately a lot more subsystems that would need the same treatment. Yes, that's exactly why the patch is needed - to find the bugs and fix them. Otherwise you'll have problems finding some places to convert to TASK_KILLABLE. CIFS and similar have to be fixed - it tends to lock the app using it, in unkillable state. > > > Also in general I have my doubts that the false positive:real bug > > > ratio of this warning is well balanced. > > > > I'll just have to disagree with you then; but both of us are making > > wild guesses. Only one way to get the real false positive percentage. > > Yes let's break things first instead of looking at the implications closely. Throwing _rare_ stack traces is not breakage. 120s task_uninterruptible in the usual case (no errors) is already broken - there are no sane loads that can invoke that IMO. A stack trace on x subsystem error is not that bad, especially as these are limited to 10 per session. Disclaimer: I am not a kernel developer, just a user.