From: Ingo Molnar <mingo@elte•hu>
To: Alexey Zaytsev <alexey.zaytsev@gmail•com>
Cc: Stephen Rothwell <sfr@canb•auug.org.au>,
linux-next@vger•kernel.org, LKML <linux-kernel@vger•kernel.org>,
Nick Piggin <nickpiggin@yahoo•com.au>
Subject: Re: linux-next: Tree for December 11
Date: Tue, 16 Dec 2008 23:23:05 +0100 [thread overview]
Message-ID: <20081216222305.GJ14787@elte.hu> (raw)
In-Reply-To: <f19298770812161421r77a10575ia956e59a52d7efb2@mail.gmail.com>
* Alexey Zaytsev <alexey.zaytsev@gmail•com> wrote:
> On Wed, Dec 17, 2008 at 00:08, Ingo Molnar <mingo@elte•hu> wrote:
>
> >>
> >> The warning can also be reproduced in qemu, so it was easy to bisect.
> >>
> >> commit 7317d7b87edb41a9135e30be1ec3f7ef817c53dd
> >> Author: Nick Piggin <nickpiggin@yahoo•com.au>
> >> 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@elte•hu>
> >>
> >> 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
next prev parent reply other threads:[~2008-12-16 22:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-11 9:04 linux-next: Tree for December 11 Stephen Rothwell
2008-12-11 12:40 ` Alexey Zaytsev
2008-12-14 14:34 ` Alexey Zaytsev
2008-12-16 21:08 ` Ingo Molnar
2008-12-16 22:21 ` Alexey Zaytsev
2008-12-16 22:23 ` Ingo Molnar [this message]
-- strict thread matches above, loose matches on Subject: below --
2009-12-11 5:01 Stephen Rothwell
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