* Alexey Zaytsev <alexey.zaytsev@xxxxxxxxx> wrote: > On Wed, Dec 17, 2008 at 00:08, Ingo Molnar <mingo@xxxxxxx> wrote: > > >> > >> The warning can also be reproduced in qemu, so it was easy to bisect. > >> > >> commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd > >> Author: Nick Piggin <nickpiggin@xxxxxxxxxxxx> > >> Date: Tue Sep 30 20:50:27 2008 +1000 > >> > >> sched: improve preempt debugging > >> > >> This patch helped me out with a problem I recently had.... > >> > >> Basically, when the kernel lock is held, then preempt_count > >> underflow does not > >> get detected until it is released which may be a long time (and arbitrarily, > >> eg at different points it may be rescheduled). If the bkl is released at > >> schedule, the resulting output is actually fairly cryptic... > >> > >> With any other lock that elevates preempt_count, it is illegal to schedule > >> under it (which would get found pretty quickly). bkl allows scheduling with > >> preempt_count elevated, which makes underflows hard to debug. > >> > >> Signed-off-by: Ingo Molnar <mingo@xxxxxxx> > >> > >> I understand that not this particular commit is buggy, but at least > >> I've got someone to add to the CC. ;) > >> > >> Also the author's e-mail looks suspicious. > > > > Suspicious in what way? > > Does not appear in signed-off-by. yes, because i applied and tested it through before Nick was comfortable with signing off on it. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
