Re: [PATCH v14 0/2] PCI/IOV: Fix SR-IOV locking races and AB-BA deadlock

[Benjamin Block]

Hey Bjorn,

On Wed, Apr 22, 2026 at 09:32:40AM +0300, Ionut Nechita (Wind River) wrote:
> From: Ionut Nechita <ionut.nechita@xxxxxxxxxxxxx>
> 
> This is v14 of the fix for the SR-IOV race between driver .remove()
> and concurrent hotplug events.
> 
--8<--
> 
> This race has been independently observed by multiple organizations:
>   - IBM (s390 platform-generated hot-unplug events racing with
>     sriov_del_vfs during PF driver unload)
>   - NVIDIA (tested by Dragos Tatulea in earlier versions)
>   - Intel (xe driver hitting lockdep warnings and deadlocks when
>     calling pci_disable_sriov from .remove)
>   - Wind River (original reporter and patch author)
> 
> Test environment:
>   - Tested on s390 by Benjamin Block and Niklas Schnelle (IBM)
>   - Tested on x86_64 with Intel and NVIDIA SR-IOV devices (earlier
>     versions)
> 
> Based on linux-next (next-20260420).
> 
--8<--
> 
> Ionut Nechita (Wind River) (2):
>   PCI/IOV: Make pci_lock_rescan_remove() reentrant and protect
>     sriov_add_vfs/sriov_del_vfs
>   PCI: Fix AB-BA deadlock between device_lock and pci_rescan_remove_lock
>     in remove_store
> 
>  drivers/pci/iov.c       |  9 +++++----
>  drivers/pci/pci-sysfs.c | 30 +++++++++++++++++++++++++++++-
>  drivers/pci/probe.c     | 18 ++++++++++++++++--
>  3 files changed, 50 insertions(+), 7 deletions(-)

do you think this patchset is ready integration? Or what do you think we'd
still need to do to get there?

This race, and especially those I fix in the follow-on patchset
https://lore.kernel.org/linux-pci/cover.1776868550.git.bblock%40linux.ibm.com/
are pretty painful on s390 with PCI hotplug. It forces us to reboot the
system, since there is no other way to get out of the deadlock.

-- 
Best Regards, Benjamin Block        /        Linux on IBM Z Kernel Development
IBM Deutschland Research & Development GmbH    /   https://www.ibm.com/privacy
Vors. Aufs.-R.: Wolfgang Wendt         /        Geschäftsführung: David Faller
Sitz der Ges.: Ehningen     /     Registergericht: AmtsG Stuttgart, HRB 243294