Re: [PATCH 5.17 127/298] driver core: Fix wait_for_device_probe() & deferred_probe_timeout interaction

[Saravana Kannan]

On Thu, Aug 17, 2023 at 4:37 AM Shreeya Patel
<shreeya.patel@xxxxxxxxxxxxx> wrote:
>
> Hi Greg,
>
> On 16/08/23 20:33, Greg Kroah-Hartman wrote:
> > On Wed, Aug 16, 2023 at 03:09:27PM +0530, Shreeya Patel wrote:
> >> On 13/06/22 15:40, Greg Kroah-Hartman wrote:
> >>> From: Saravana Kannan<saravanak@xxxxxxxxxx>
> >>>
> >>> [ Upstream commit 5ee76c256e928455212ab759c51d198fedbe7523 ]
> >>>
> >>> Mounting NFS rootfs was timing out when deferred_probe_timeout was
> >>> non-zero [1].  This was because ip_auto_config() initcall times out
> >>> waiting for the network interfaces to show up when
> >>> deferred_probe_timeout was non-zero. While ip_auto_config() calls
> >>> wait_for_device_probe() to make sure any currently running deferred
> >>> probe work or asynchronous probe finishes, that wasn't sufficient to
> >>> account for devices being deferred until deferred_probe_timeout.
> >>>
> >>> Commit 35a672363ab3 ("driver core: Ensure wait_for_device_probe() waits
> >>> until the deferred_probe_timeout fires") tried to fix that by making
> >>> sure wait_for_device_probe() waits for deferred_probe_timeout to expire
> >>> before returning.
> >>>
> >>> However, if wait_for_device_probe() is called from the kernel_init()
> >>> context:
> >>>
> >>> - Before deferred_probe_initcall() [2], it causes the boot process to
> >>>     hang due to a deadlock.
> >>>
> >>> - After deferred_probe_initcall() [3], it blocks kernel_init() from
> >>>     continuing till deferred_probe_timeout expires and beats the point of
> >>>     deferred_probe_timeout that's trying to wait for userspace to load
> >>>     modules.
> >>>
> >>> Neither of this is good. So revert the changes to
> >>> wait_for_device_probe().
> >>>
> >>> [1] -https://lore.kernel.org/lkml/TYAPR01MB45443DF63B9EF29054F7C41FD8C60@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> >>> [2] -https://lore.kernel.org/lkml/YowHNo4sBjr9ijZr@dev-arch.thelio-3990X/
> >>> [3] -https://lore.kernel.org/lkml/Yo3WvGnNk3LvLb7R@xxxxxxxxxxxxx/
> >> Hi Saravana, Greg,
> >>
> >>
> >> KernelCI found this patch causes the baseline.bootrr.deferred-probe-empty test to fail on r8a77960-ulcb,
> >> see the following details for more information.
> >>
> >> KernelCI dashboard link:
> >> https://linux.kernelci.org/test/plan/id/64d2a6be8c1a8435e535b264/
> >>
> >> Error messages from the logs :-
> >>
> >> + UUID=11236495_1.5.2.4.5
> >> + set +x
> >> + export 'PATH=/opt/bootrr/libexec/bootrr/helpers:/lava-11236495/1/../bin:/sbin:/usr/sbin:/bin:/usr/bin'
> >> + cd /opt/bootrr/libexec/bootrr
> >> + sh helpers/bootrr-auto
> >> e6800000.ethernet
> >> e6700000.dma-controller
> >> e7300000.dma-controller
> >> e7310000.dma-controller
> >> ec700000.dma-controller
> >> ec720000.dma-controller
> >> fea20000.vsp
> >> feb00000.display
> >> fea28000.vsp
> >> fea30000.vsp
> >> fe9a0000.vsp
> >> fe9af000.fcp
> >> fea27000.fcp
> >> fea2f000.fcp
> >> fea37000.fcp
> >> sound
> >> ee100000.mmc
> >> ee140000.mmc
> >> ec500000.sound
> >> /lava-11236495/1/../bin/lava-test-case
> >> <8>[   17.476741] <LAVA_SIGNAL_TESTCASE TEST_CASE_ID=deferred-probe-empty RESULT=fail>
> >>
> >> Test case failing :-
> >> Baseline Bootrr deferred-probe-empty test -https://github.com/kernelci/bootrr/blob/main/helpers/bootrr-generic-tests
> >>
> >> Regression Reproduced :-
> >>
> >> Lava job after reverting the commit 5ee76c256e92
> >> https://lava.collabora.dev/scheduler/job/11292890
> >>
> >>
> >> Bisection report from KernelCI can be found at the bottom of the email.
> >>
> >> Thanks,
> >> Shreeya Patel
> >>
> >> #regzbot introduced: 5ee76c256e92
> >> #regzbot title: KernelCI: Multiple devices deferring on r8a77960-ulcb
> >>
> >> ---------------------------------------------------------------------------------------------------------------------------------------------------
> >>
> >> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * **
> >> * If you do send a fix, please include this trailer: *
> >> * Reported-by: "kernelci.org bot" <bot@...> *
> >> * *
> >> * Hope this helps! *
> >> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
> >>
> >> stable-rc/linux-5.10.y bisection: baseline.bootrr.deferred-probe-empty on
> >> r8a77960-ulcb
> > You are testing 5.10.y, yet the subject says 5.17?
> >
> > Which is it here?
>
> Sorry, I accidentally used the lore link for 5.17 while reporting this
> issue,
> but this test does fail on all the stable releases from 5.10 onwards.
>
> stable 5.15 :-
> https://linux.kernelci.org/test/case/id/64dd156a5ac58d0cf335b1ea/
> mainline :-
> https://linux.kernelci.org/test/case/id/64dc13d55cb51357a135b209/
>

Shreeya, can you try the patch Geert suggested and let us know if it
helps? If not, then I can try to take a closer look.

-Saravana