Re: 2.6.35-rc2-git2: Reported regressions from 2.6.34

Rafael J. Wysocki
2010-06-09T08:55:38Z

On Wednesday 09 June 2010, Jens Axboe wrote:
> On 2010-06-09 03:53, Linus Torvalds wrote:
> >> Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=16129
> >> Subject : BUG: using smp_processor_id() in preemptible [00000000] code: jbd2/sda2
> >> Submitter : Jan Kreuzer <kontrollator@gmx.de>
> >> Date : 2010-06-05 06:15 (4 days old)
> >
> > This seems to have been introduced by
> >
> > commit 7cbaef9c83e58bbd4bdd534b09052b6c5ec457d5
> > Author: Ingo Molnar <mingo@elte.hu>
> > Date: Sat Nov 8 17:05:38 2008 +0100
> >
> > sched: optimize sched_clock() a bit
> >
> > sched_clock() uses cycles_2_ns() needlessly - which is an irq-disabling
> > variant of __cycles_2_ns().
> >
> > Most of the time sched_clock() is called with irqs disabled already.
> > The few places that call it with irqs enabled need to be updated.
> >
> > Signed-off-by: Ingo Molnar <mingo@elte.hu>
> >
> > and this seems to be one of those calling cases that need to be updated.
> >
> > Ingo? The call trace is:
> >
> > BUG: using smp_processor_id() in preemptible [00000000] code: jbd2/sda2-8/337
> > caller is native_sched_clock+0x3c/0x68
> > Pid: 337, comm: jbd2/sda2-8 Not tainted 2.6.35-rc1jan+ #4
> > Call Trace:
> > [<ffffffff812362c5>] debug_smp_processor_id+0xc9/0xe4
> > [<ffffffff8101059d>] native_sched_clock+0x3c/0x68
> > [<ffffffff8101043d>] sched_clock+0x9/0xd
> > [<ffffffff81212d7a>] blk_rq_init+0x97/0xa3
> > [<ffffffff81214d71>] get_request+0x1c4/0x2d0
> > [<ffffffff81214ea6>] get_request_wait+0x29/0x1a6
> > [<ffffffff81215537>] __make_request+0x338/0x45b
> > [<ffffffff812147c2>] generic_make_request+0x2bb/0x330
> > [<ffffffff81214909>] submit_bio+0xd2/0xef
> > [<ffffffff811413cb>] submit_bh+0xf4/0x116
> > [<ffffffff81144853>] block_write_full_page_endio+0x89/0x96
> > [<ffffffff81144875>] block_write_full_page+0x15/0x17
> > [<ffffffff8119b00a>] ext4_writepage+0x356/0x36b
> > [<ffffffff810e1f91>] __writepage+0x1a/0x39
> > [<ffffffff810e32a6>] write_cache_pages+0x20d/0x346
> > [<ffffffff810e3406>] generic_writepages+0x27/0x29
> > [<ffffffff811ca279>] journal_submit_data_buffers+0x110/0x17d
> > [<ffffffff811ca986>] jbd2_journal_commit_transaction+0x4cb/0x156d
> > [<ffffffff811d0cba>] kjournald2+0x147/0x37a
> >
> > (from the bugzilla thing)
>
> This should be fixed by commit 28f4197e which was merged on friday.

Thanks, closed.

Rafael