[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20100601065500.GA7876@elte.hu>
Date: Tue, 1 Jun 2010 08:55:00 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Jens Axboe <axboe@...nel.dk>
Cc: Peter Zijlstra <peterz@...radead.org>, piotr@...owicz.com,
linux-kernel@...r.kernel.org, Divyesh Shah <dpshah@...gle.com>
Subject: Re: BUG: using smp_processor_id() in preemptible [00000000] code:
icedove-bin/5449
* Jens Axboe <axboe@...nel.dk> wrote:
> On Tue, Jun 01 2010, Ingo Molnar wrote:
> >
> > * Peter Zijlstra <peterz@...radead.org> wrote:
> >
> > > On Mon, 2010-05-24 at 05:03 +0200, Piotr Hosowicz wrote:
> > > > [ 720.313607] BUG: using smp_processor_id() in preemptible [00000000] code: icedove-bin/5449
> > > > [ 720.313612] caller is native_sched_clock+0x3c/0x68
> > > > [ 720.313616] Pid: 5449, comm: icedove-bin Tainted: P 2.6.34-20100524-0407 #1
> > > > [ 720.313618] Call Trace:
> > > > [ 720.313624] [<ffffffff811a533b>] debug_smp_processor_id+0xc7/0xe0
> > > > [ 720.313629] [<ffffffff81009b87>] native_sched_clock+0x3c/0x68
> > > > [ 720.313634] [<ffffffff81009a4d>] sched_clock+0x9/0xd
> > > > [ 720.313637] [<ffffffff811823ec>] blk_rq_init+0x92/0x9d
> > > > [ 720.313641] [<ffffffff81184227>] get_request+0x1bf/0x2c7
> > > > [ 720.313646] [<ffffffff8118435c>] get_request_wait+0x2d/0x19d
> > >
> > > This comes from wreckage in the blk tree..
> > >
> > > ---
> > > commit 9195291e5f05e01d67f9a09c756b8aca8f009089
> > > Author: Divyesh Shah <dpshah@...gle.com>
> > > Date: Thu Apr 1 15:01:41 2010 -0700
> > >
> > > blkio: Increment the blkio cgroup stats for real now
> >
> > Jens, this regression is still in .35-rc1 and triggers in about 25% of all
> > -tip boot tests.
> >
> > The above commit is using sched_clock() in an unsafe way - please fix it or
> > revert it.
> >
> > The local_clock() changes PeterZ is working on are still WIP, it's not sure
> > we'll have it before .36.
>
> OK, I guess we'll have to solve this differently for .35 - I'll cook up
> something simple, if need be revert the change.
I suspect you can put get_cpu/put_cpu around it and use cpu_clock(). The
cross-CPU effects will still be there and there might be weird stats.
Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists