Re: [PATCH 4.9 00/25] 4.9.316-rc1 review

Greg Kroah-Hartman
2022-05-24T15:06:27Z

On Tue, May 24, 2022 at 03:55:58PM +0100, Jon Hunter wrote:
>
> On 24/05/2022 13:09, Greg Kroah-Hartman wrote:
>
> ...
>
> > > I am seeing a boot regression on tegra124-jetson-tk1 and reverting the above
> > > commit is fixing the problem. This also appears to impact linux-4.14.y,
> > > 4.19.y and 5.4.y.
> > >
> > > Test results for stable-v4.9:
> > > 8 builds: 8 pass, 0 fail
> > > 18 boots: 16 pass, 2 fail
> > > 18 tests: 18 pass, 0 fail
> > >
> > > Linux version: 4.9.316-rc1-gbe4ec3e3faa1
> > > Boards tested: tegra124-jetson-tk1, tegra20-ventana,
> > > tegra210-p2371-2180, tegra30-cardhu-a04
> > >
> > > Boot failures: tegra124-jetson-tk1
> >
> > Odd. This is also in 5.10.y, right? No issues there? Are we missing
> > something?
>
>
> Actually, the more I look at this, the more I see various intermittent
> reports with this and it is also impacting the mainline.
>
> The problem is that the commit in question is causing a ton of messages to
> be printed a boot and this sometimes is causing the boot test to fail
> because the boot is taking too long. The console shows ...
>
> [ 1233.327547] CPU0: Spectre BHB: using loop workaround
> [ 1233.327795] CPU1: Spectre BHB: using loop workaround
> [ 1233.328270] CPU1: Spectre BHB: using loop workaround
> [ 1233.328700] CPU1: Spectre BHB: using loop workaround
> [ 1233.355477] CPU2: Spectre BHB: using loop workaround
> ** 7 printk messages dropped **
> [ 1233.366271] CPU0: Spectre BHB: using loop workaround
> [ 1233.366580] CPU0: Spectre BHB: using loop workaround
> [ 1233.366815] CPU1: Spectre BHB: using loop workaround
> [ 1233.405475] CPU1: Spectre BHB: using loop workaround
> [ 1233.405874] CPU0: Spectre BHB: using loop workaround
> [ 1233.406041] CPU1: Spectre BHB: using loop workaround
> ** 1 printk messages dropped **
>
> There is a similar report of this [0] and I believe that we need a similar
> fix for the above prints as well. I have reported this to Ard [1]. So I am
> not sure that these Spectre BHB patches are quite ready for stable.

These patches are quite small, and just enable it for this known-broken
cpu type.

If there is an issue enabling it for this cpu type, then we can work on
that upstream, but there shouldn't be a reason to prevent this from
being merged now, especially given that it is supposed to be fixing a
known issue.

thanks,

greg k-h