Re: [BUG] PCIe bridge resource allocation creates invalid limit addresses after Secondary Bus Reset recovery

[Shawn Jin]

Hi Bjorn,

I agree we should work on the latest kernel instead. I'll try the latest kernel and report if similar issue exists.

Thanks,
Shawn.

________________________________________
From: Bjorn Helgaas <helgaas@xxxxxxxxxx>
Sent: Thursday, March 12, 2026 10:34 AM
To: Shawn Jin <shawn.jin@xxxxxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx <linux-pci@xxxxxxxxxxxxxxx>; Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Subject: Re: [BUG] PCIe bridge resource allocation creates invalid limit addresses after Secondary Bus Reset recovery
 
[EXTERNAL EMAIL]

On Thu, Mar 12, 2026 at 12:02:14AM +0000, Shawn Jin wrote:
> On Wed, Mar 11, 2026 at 10:00:39PM +0000, Shawn Jin wrote:
> > I'm reporting a potential critical bug in the Linux kernel's PCIe
> > resource allocation code that creates invalid bridge window limit
> > addresses during hotplug re-enumeration after Secondary Bus Reset
> > (SBR) recovery.
>
> Thanks for the report and the repro and debugging information!
>
> > ## AFFECTED KERNEL VERSIONS
> > - Confirmed: 5.15.0, 6.8.0 (Ubuntu 6.8.0-88-generic, 6.8.0-90-generic)
> > - Likely affected: All recent kernels including 6.19
>
> Do you know of any kernels that are *not* affected?  If you do, we
> could bisect.
>
> <SJ> I haven't tried the latest kernel 6.19 yet. I'm planning to
> install the openSUSE Tumbleweed with kernel 6.19.

I didn't notice at first, but AFAICS the most recent kernel you've
actually tested is v6.8, and "6.19 likely affected" is just
speculation.

There have been a lot of resource assignment changes since then, so
I doubt it's worth testing/debugging these old kernels until we
actually know the problem happens on v6.19 or v7.0-rc1.

IMO we should start by debugging the current kernel, fix the issue
there, then decide about backporting.

Bjorn