On 2017/8/15 22:03, Eric Dumazet wrote: > On Tue, 2017-08-15 at 06:58 -0700, Eric Dumazet wrote: >> On Mon, 2017-08-14 at 22:15 -0700, David Miller wrote: >>> From: Ding Tianhong <dingtianh...@huawei.com> >>> Date: Tue, 15 Aug 2017 11:23:22 +0800 >>> >>>> Some devices have problems with Transaction Layer Packets with the Relaxed >>>> Ordering Attribute set. This patch set adds a new PCIe Device Flag, >>>> PCI_DEV_FLAGS_NO_RELAXED_ORDERING, a set of PCI Quirks to catch some known >>>> devices with Relaxed Ordering issues, and a use of this new flag by the >>>> cxgb4 driver to avoid using Relaxed Ordering with problematic Root Complex >>>> Ports. >>> ... >>> >>> Series applied, thanks. >> >> I got a NULL deref in pci_find_pcie_root_port() >> > > This was : > > [ 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 > [ 4.451002] ret_from_fork+0x27/0x40 > [ 4.457004] Code: 85 d2 74 27 80 7a 4a 00 74 21 48 89 d0 48 89 c2 f6 80 1b > 09 00 00 10 74 07 48 8b 90 a0 0a 00 00 48 8b 52 10 48 83 7a 10 00 75 d0 <0f> > b7 50 50 5d 81 e2 f0 00 00 00 83 fa 40 ba 00 00 00 00 48 0f > [ 4.474012] RIP: pci_find_pcie_root_port+0x62/0x80 RSP: ffffa51ec0007ab8 > [ 4.481004] CR2: 0000000000000050 > [ 4.484001] ---[ end trace 6f9be6a057581199 ]--- > [ 4.488001] Kernel panic - not syncing: Fatal exception > [ 4.494013] Rebooting in 10 seconds.. > [ 4.494013] ACPI MEMORY or I/O RESET_REG. > >> >> This local hack seems to fix the issue. >> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index >> af0cc3456dc1b48b1325c06c5edd2ca8cc22a640..cfd8eb5a3d0ba8347d44952ffab28d9c761044d3 >> 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -522,7 +522,7 @@ 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; >
It is very strange that I could not reproduce this problem on my server which is Xeon 2690v3, but it is really a obviously issue when the dev could not find a upstream bridge in the pci_find_pcie_root_port(), so the better way is just like your did in this patch. Thanks. Regards Tianhong > > > . >
