On Thu, 29 Jan 2015 17:25:07 Linus Torvalds wrote: > On Thu, Jan 29, 2015 at 5:12 PM, Linus Torvalds wrote: > > > > The WARN() was already changed to a WARN_ONCE(). > > Oh, but I notice that the "__set_current_state(TASK_RUNNING) ends up > always happening. > > So I think the right fix is to: > > - warn once like we do > > - but *not* do that __set_current_state() which was always total > crap anyway > > Why do I say "total crap"? Because of two independent issues: > > (a) it actually changes behavior for a debug vs non-debug kernel, > which is a really bad idea to begin with > > (b) it's really wrong. The whole "nested sleep" case was never a > major bug to begin with, just a possible inefficiency where constant > nested sleeps would possibly make the outer sleep not sleep. But that > "could possibly make" case was the unlikely case, and the debug patch > made it happen *all* the time by explicitly setting things running. > > So I think the proper patch is the attached. > > The comment is also crap. The comment says > > "Blocking primitives will set (and therefore destroy) > current->state [...]" > > but the reality is that they *may* set it, and only in the unlikely > slow-path where they actually block. > > So doing this in "__may_sleep()" is just bogus and horrible horrible > crap. It turns the "harmless ugliness" into a real *harmful* bug. The > key word of "__may_sleep()" is that "MAY" part. It's a debug thing to > make relatively rare cases show up. > > PeterZ, please don't make "debugging" patches like this. Ever again. > Because this was just stupid, and it took me too long to realize that > despite the warning being shut up, the debug patch was still actively > doing bad bad things. > > Ingo, maybe you'd want to apply this through the scheduler tree, the > way you already did the WARN_ONCE() thing. > > Bruno, does this finally actually fix your pccard thing?
I will report back on Wednesday when I'm back home from FOSDEM. I don't have the affected machine at hand at the moment. Thanks for looking into it! Bruno > Linus -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
