Re: [PATCH 01/33] PCI: Prepare to protect against concurrent isolated cpuset change

Bjorn Helgaas
2026-01-07T23:39:57Z

On Thu, Jan 08, 2026 at 12:30:13AM +0100, Frederic Weisbecker wrote:
> Le Wed, Jan 07, 2026 at 01:05:34PM -0600, Bjorn Helgaas a écrit :
> > On Thu, Jan 01, 2026 at 11:13:26PM +0100, Frederic Weisbecker wrote:
> > > HK_TYPE_DOMAIN will soon integrate cpuset isolated partitions and
> > > therefore be made modifiable at runtime. Synchronize against the cpumask
> > > update using RCU.
> > >
> > > The RCU locked section includes both the housekeeping CPU target
> > > election for the PCI probe work and the work enqueue.
> > >
> > > This way the housekeeping update side will simply need to flush the
> > > pending related works after updating the housekeeping mask in order to
> > > make sure that no PCI work ever executes on an isolated CPU. This part
> > > will be handled in a subsequent patch.
> > >
> > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> >
> > Just FYI, Jinhui posted a series that touches this same code and might
> > need some coordination:
> >
> > https://lore.kernel.org/r/20260107175548.1792-1-guojinhui.liam@bytedance.com
> >
> > IIUC, Jinhui's series adds some more NUMA smarts in the driver core
> > sync probing path and removes corresponding NUMA code from the PCI
> > core probe path.
>
> I see. I can't drop my change, otherwise my series alone could crash
> dereferencing garbage. But Jinhui's series removes the need for my
> changes.
>
> So an unpleasant conflict will happen in -next (and if everything
> goes well, further in next merge window) and it should be resolved
> with simply ignoring my changes and only apply those of Jinhui.

I don't want to derail your series, and I don't think you need to
change anything right now. Jinhui's series is early and might not be
ready to merge until after yours, which should be fine.

Bjorn