On Thu, Oct 03, 2024 at 10:43:41AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
>
> Since adding the PCI power control code, we may end up with a race
> between the pwrctl platform device rescanning the bus and the host
> controller probe function. The latter needs to take the rescan lock when
> adding devices or we may end up in an undefined state having two
> incompletely added devices and hit the following crash when trying to
> remove the device over sysfs:
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> Internal error: Oops: 0000000096000004 [#1] SMP
> Call trace:
> __pi_strlen+0x14/0x150
> kernfs_find_ns+0x80/0x13c
> kernfs_remove_by_name_ns+0x54/0xf0
> sysfs_remove_bin_file+0x24/0x34
> pci_remove_resource_files+0x3c/0x84
> pci_remove_sysfs_dev_files+0x28/0x38
> pci_stop_bus_device+0x8c/0xd8
> pci_stop_bus_device+0x40/0xd8
> pci_stop_and_remove_bus_device_locked+0x28/0x48
> remove_store+0x70/0xb0
> dev_attr_store+0x20/0x38
> sysfs_kf_write+0x58/0x78
> kernfs_fop_write_iter+0xe8/0x184
> vfs_write+0x2dc/0x308
> ksys_write+0x7c/0xec
>
Thanks for adding the crash log. It always helps to have the log in patch
description to find *this* patch.
> Reported-by: Konrad Dybcio <konradybcio@xxxxxxxxxx>
> Tested-by: Konrad Dybcio <konradybcio@xxxxxxxxxx>
> Fixes: 4565d2652a37 ("PCI/pwrctl: Add PCI power control core code")
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
- Mani
> ---
> v1 -> v2:
> - improve the commit message, add example stack trace
>
> drivers/pci/probe.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 4f68414c3086..f1615805f5b0 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -3105,7 +3105,9 @@ int pci_host_probe(struct pci_host_bridge *bridge)
> list_for_each_entry(child, &bus->children, node)
> pcie_bus_configure_settings(child);
>
> + pci_lock_rescan_remove();
> pci_bus_add_devices(bus);
> + pci_unlock_rescan_remove();
> return 0;
> }
> EXPORT_SYMBOL_GPL(pci_host_probe);
> --
> 2.30.2
>
>
--
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