Eric report a oops when booting the system after applying
the commit a99b646afa8a ("PCI: Disable PCIe Relaxed..."):
[ 4.241029] BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
[ 4.247001] IP: pci_find_pcie_root_port+0x62/0x80
[ 4.253011] PGD 0
[ 4.253011] P4D 0
[ 4.253011]
[ 4.258013] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
[ 4.262015] Modules linked in:
[ 4.265005] CPU: 31 PID: 1 Comm: swapper/0 Not tainted 4.13.0-dbx-DEV #316
[ 4.271002] Hardware name: Intel RML,PCH/Iota_QC_19, BIOS 2.40.0 06/22/2016
[ 4.279002] task: ffffa2ee38cfa040 task.stack: ffffa51ec0004000
[ 4.285001] RIP: 0010:pci_find_pcie_root_port+0x62/0x80
[ 4.290012] RSP: 0000:ffffa51ec0007ab8 EFLAGS: 00010246
[ 4.295003] RAX: 0000000000000000 RBX: ffffa2ee36bae000 RCX: 0000000000000006
[ 4.303002] RDX: 000000000000081c RSI: ffffa2ee38cfa8c8 RDI: ffffa2ee36bae000
[ 4.310013] RBP: ffffa51ec0007b58 R08: 0000000000000001 R09: 0000000000000000
[ 4.317001] R10: 0000000000000000 R11: 0000000000000000 R12: ffffa51ec0007ad0
[ 4.324005] R13: ffffa2ee36bae098 R14: 0000000000000002 R15: ffffa2ee37204818
[ 4.331002] FS: 0000000000000000(0000) GS:ffffa2ee3fcc0000(0000) knlGS:0000000000000000
[ 4.339002] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 4.345001] CR2: 0000000000000050 CR3: 000000401000f000 CR4: 00000000001406e0
[ 4.351002] Call Trace:
[ 4.354012] ? pci_configure_device+0x19f/0x570
[ 4.359002] ? pci_conf1_read+0xb8/0xf0
[ 4.363002] ? raw_pci_read+0x23/0x40
[ 4.366011] ? pci_read+0x2c/0x30
[ 4.370014] ? pci_read_config_word+0x67/0x70
[ 4.374012] pci_device_add+0x28/0x230
[ 4.378012] ? pci_vpd_f0_read+0x50/0x80
[ 4.382014] pci_scan_single_device+0x96/0xc0
[ 4.386012] pci_scan_slot+0x79/0xf0
[ 4.389001] pci_scan_child_bus+0x31/0x180
[ 4.394014] acpi_pci_root_create+0x1c6/0x240
[ 4.398013] pci_acpi_scan_root+0x15f/0x1b0
[ 4.402012] acpi_pci_root_add+0x2e6/0x400
[ 4.406012] ? acpi_evaluate_integer+0x37/0x60
[ 4.411002] acpi_bus_attach+0xdf/0x200
[ 4.415002] acpi_bus_attach+0x6a/0x200
[ 4.418014] acpi_bus_attach+0x6a/0x200
[ 4.422013] acpi_bus_scan+0x38/0x70
[ 4.426011] acpi_scan_init+0x10c/0x271
[ 4.429001] acpi_init+0x2fa/0x348
[ 4.433004] ? acpi_sleep_proc_init+0x2d/0x2d
[ 4.437001] do_one_initcall+0x43/0x169
[ 4.441001] kernel_init_freeable+0x1d0/0x258
[ 4.445003] ? rest_init+0xe0/0xe0
[ 4.449001] kernel_init+0xe/0x150
====================== cut here =============================
It looks like the pci_find_pcie_root_port() was trying to
find the Root Port for the PCI device which is the Root
Port already, it will return NULL and trigger the problem,
so check the highest_pcie_bridge to fix thie problem.
Fixes: a99b646afa8a ("PCI: Disable PCIe Relaxed Ordering if unsupported")
Reported-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
---
drivers/pci/pci.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index af0cc34..7e2022f 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -522,7 +522,8 @@ struct pci_dev *pci_find_pcie_root_port(struct pci_dev *dev)
bridge = pci_upstream_bridge(bridge);
}
- if (pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
+ if (highest_pcie_bridge &&
+ pci_pcie_type(highest_pcie_bridge) != PCI_EXP_TYPE_ROOT_PORT)
return NULL;
return highest_pcie_bridge;
--
1.8.3.1
