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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/19/26 05:31, Niklas Schnelle wrote: > On Wed, 2026-03-18 at 23:03 +0200, Ionut Nechita (Wind River) wrote: >> From: Ionut Nechita >> >> Hi Bjorn, >> >> This is v10 of the fix for the SR-IOV race between driver .remove() >> and concurrent hotplug events. v10 adds a second patch to fix the >> AB-BA deadlock between device_lock and pci_rescan_remove_lock that >> was reported by Guenter Roeck (via Google's AI review agent) and >> confirmed by Benjamin Block. >> >> The AB-BA deadlock: >> >> CPU0 (remove_store) CPU1 (unbind_store) >> -------------------- -------------------- >> pci_lock_rescan_remove() >> device_lock() >> driver .remove() >> sriov_del_vfs() >> pci_lock_rescan_remove() <-- WAITS >> pci_stop_bus_device() >> device_release_driver() >> device_lock() <-- WAITS >> >> Patch 2/2 fixes this by calling device_release_driver() in >> remove_store() before pci_stop_and_remove_bus_device_locked(), so >> that the driver is already unbound when pci_rescan_remove_lock is >> acquired. Both paths then take locks in the same order: device_lock >> first, then pci_rescan_remove_lock. >> >> Note: the concurrent unbind_store + hotplug-event case (where the >> hotplug handler takes pci_rescan_remove_lock before device_lock) >> remains a known limitation. This is a pre-existing issue that >> Benjamin Block is addressing separately in: >> https://lore.kernel.org/linux-pci/354b9e4a54ced67f3c89df198041df19434fe4c8.1773235561.git.bblock@linux.ibm.com/ >> > --- snip --- >> >> Ionut Nechita (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 | 20 +++++++++++++++++++- >> drivers/pci/probe.c | 11 +++++++++-- >> 3 files changed, 33 insertions(+), 7 deletions(-) >> >> -- >> 2.43.0 > > Hi Ionut, > > For your awareness, I saw that this series has some findings on > Google's new Sashiko AI reviewing tool[0]. At a quick glance the > findings seem like at least reasonable concerns to me. I'm still > looking at this independently also of course. > It is almost scary to see how many problems Sashiko is able to find. The AB-BA deadlock that the second patch in the series tries to fix was reported by a prototype version of it when running it on an LTS backport. Guenter