Re: Regression with a0747a859ef6 ("bdi: add error handle for bdi_debug_register")

[weiping zhang <zwp10758@gmail.com>]

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2017年12月22日星期五，James Bottomley <James.Bottomley@hansenpartnership.com> 写道：

> On Thu, 2017-12-21 at 10:02 -0700, Jens Axboe wrote:
> > On 12/21/17 9:42 AM, Bruno Wolff III wrote:
> > >
> > > On Thu, Dec 21, 2017 at 23:48:19 +0800,
> > >   weiping zhang <zwp10758@gmail.com> wrote:
> > > >
> > > > >
> > > > > output you want. I never saw it for any kernels I compiled
> > > > > myself. Only when I test kernels built by Fedora do I see it.
> > > > > see it every boot ?
> > >
> > > I don't look every boot. The warning gets scrolled of the screen.
> > > Once I see the CPU hang warnings I know the boot is failing. I
> > > don't always look at journalctl later to see what's there.
> >
> > I'm going to revert a0747a859ef6 for now, since we're now 8 days into
> > this and no progress has been made on fixing it.
>
> There is a dummy function in this file, if DEBUG_FS =N，

> I think this is correct.  If you build the kernel with
> CONFIG_DEBUG_FS=N, you're definitely going to get the same hang
> (because the debugfs_ functions fail with -ENODEV and the bdi will
> never get registered).  This alone leads me to suspect the commit is
> bogus because it's a randconfig/test accident waiting to happen.
> We should still root cause the debugfs failure in this case, but I
> really think debugfs files should be treated as optional, so a failure
> in setting them up should translate to some sort of warning not a
> failure to set up the bdi.
>
> Yes, its just for debug, has no effect on gendisk(include weiteback),

> James
>
>

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