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Date:   Wed, 25 May 2022 09:11:56 +0200
From:   Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To:     Saravana Kannan <saravanak@google.com>
Cc:     Nathan Chancellor <nathan@kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Rob Herring <robh@kernel.org>,
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Subject: Re: [PATCH v1] driver core: Extend deferred probe timeout on driver
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On 2022-05-24 10:46:49 [-0700], Saravana Kannan wrote:
> > Removing probe_timeout_waitqueue (as suggested) or setting the timeout
> > to 0 avoids the delay.
>=20
> In your case, I think it might be working as intended? Curious, what
> was the call stack in your case where it was blocked?

Why is then there 10sec delay during boot? The backtrace is
|------------[ cut here ]------------
|WARNING: CPU: 4 PID: 1 at drivers/base/dd.c:742 wait_for_device_probe+0x30=
/0x110
|Modules linked in:
|CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.18.0-rc5+ #154
|RIP: 0010:wait_for_device_probe+0x30/0x110
|Call Trace:
| <TASK>
| prepare_namespace+0x2b/0x160
| kernel_init_freeable+0x2b3/0x2dd
| kernel_init+0x11/0x110
| ret_from_fork+0x22/0x30
| </TASK>

Looking closer, it can't access init. This in particular box boots
directly the kernel without an initramfs so the kernel later mounts
/dev/sda1 and everything is good.  So that seems to be the reason=E2=80=A6
My other machine with an initramfs does not show this problem.

> -Saravana

Sebastian