Re: [regression]Boot Hang on Kernel 6.1.83+ with Dell PowerEdge R770 and Intel Xeon 6710E

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Oct 10, 2024 at 12:10:49PM +0200, Jinpu Wang wrote:
> Hi Greg,
> 
> 
> On Thu, Oct 10, 2024 at 11:31 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Thu, Oct 10, 2024 at 11:13:42AM +0200, Jinpu Wang wrote:
> > > Hi Greg,
> > >
> > > On Thu, Oct 10, 2024 at 11:07 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > >
> > > > On Thu, Oct 10, 2024 at 09:31:37AM +0200, Jinpu Wang wrote:
> > > > > Hello all,
> > > > >
> > > > > We are experiencing a boot hang issue when booting kernel version
> > > > > 6.1.83+ on a Dell Inc. PowerEdge R770 equipped with an Intel Xeon
> > > > > 6710E processor. After extensive testing and use of `git bisect`, we
> > > > > have traced the issue to commit:
> > > > >
> > > > > `586e19c88a0c ("iommu/vt-d: Retrieve IOMMU perfmon capability information")`
> > > > >
> > > > > This commit appears to be part of a larger patchset, which can be found here:
> > > > > [Patchset on lore.kernel.org](https://lore.kernel.org/lkml/7c4b3e4e-1c5d-04f1-1891-84f686c94736@linux.intel.com/T/)
> > > > >
> > > > > We attempted to boot with the `intel_iommu=off` option, but the system
> > > > > hangs in the same manner. However, the system boots successfully after
> > > > > disabling `CONFIG_INTEL_IOMMU_PERF_EVENTS`.
> > > >
> > > > Is there any error messages?  Does the latest 6.6.y tree work properly?
> > > > If so, why not just use that, no new hardware should be using older
> > > > kernel trees anyway :)
> > > No error, just hang, I've removed "quiet" and added "debug".
> > > Yes, the latest 6.6.y tree works for this, but there are other
> > > problems/dependency we have to solve.
> >
> > Ok, that implies that we need to add some other patch to 6.1.y, OR we
> > can revert it from 6.1.y.  Let me know what you think is the better
> > thing to do.
> >
> I think better to revert both:
> 8c91a4bfc7f8 ("iommu: Fix compilation without CONFIG_IOMMU_INTEL")
> 586e19c88a0c ("iommu/vt-d: Retrieve IOMMU perfmon capability information")

Can you send reverts for these, or do you need us to do this for you?

thanks,

greg k-h