On Mon, Dec 09, 2019 at 01:33:49PM +0000, Nicholas Johnson wrote: > On Mon, Dec 09, 2019 at 03:12:39PM +0200, mika.westerberg@xxxxxxxxxxxxxxx wrote: > > On Mon, Dec 09, 2019 at 12:34:04PM +0000, Nicholas Johnson wrote: > > > Hi, > > > > > > I have compiled Linux v5.5-rc1 and thought all was good until I > > > hot-removed a Gigabyte Aorus eGPU from Thunderbolt. The driver for the > > > GPU was not loaded (blacklisted) so the crash is nothing to do with the > > > GPU driver. > > > > > > We had: > > > - kernel NULL pointer dereference > > > - refcount_t: underflow; use-after-free. > > > > > > Attaching dmesg for now; will bisect and come back with results. > > > > Looks like something related to iommu. Does it work if you disable it? > > (intel_iommu=off in the command line). > On Mon, Dec 09, 2019 at 03:12:39PM +0200, mika.westerberg@xxxxxxxxxxxxxxx wrote: > > On Mon, Dec 09, 2019 at 12:34:04PM +0000, Nicholas Johnson wrote: > > > Hi, > > > > > > I have compiled Linux v5.5-rc1 and thought all was good until I > > > hot-removed a Gigabyte Aorus eGPU from Thunderbolt. The driver for the > > > GPU was not loaded (blacklisted) so the crash is nothing to do with the > > > GPU driver. > > > > > > We had: > > > - kernel NULL pointer dereference > > > - refcount_t: underflow; use-after-free. > > > > > > Attaching dmesg for now; will bisect and come back with results. > > > > Looks like something related to iommu. Does it work if you disable it? > > (intel_iommu=off in the command line). > I thought it could be that, too. > > The attachment "dmesg-4" from the original email is with iommu parameters. > The attachment "dmesg-5" from the original email is with no iommu parameters. > Attaching here "dmesg-6" with the iommu explicitly set off like you said. > > No difference, still broken. Although, with iommu off, there are less stack traces. > > Could it be sysfs-related? Bisect would probably be the best option to find the culprit commit. There are couple of commits done for pciehp so reverting them one by one may help as well: 87d0f2a5536f PCI: pciehp: Prevent deadlock on disconnect 75fcc0ce72e5 PCI: pciehp: Do not disable interrupt twice on suspend b94ec12dfaee PCI: pciehp: Refactor infinite loop in pcie_poll_cmd() 157c1062fcd8 PCI: pciehp: Avoid returning prematurely from sysfs requests
