Greetings, I got the below dmesg and the first bad commit is git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux versatile commit 003b5e6f33242288b3da627ac8a9fffdc61067a0 Author: Liviu Dudau AuthorDate: Fri Mar 14 15:34:29 2014 +0000 Commit: Rob Herring CommitDate: Thu Mar 27 17:00:57 2014 -0500 pci: Create pci_host_bridge before its associated bus in pci_create_root_bus. Before commit 7b5436635800 the pci_host_bridge was created before the root bus. As that commit has added a needless dependency on the bus for pci_alloc_host_bridge() the creation order has been changed for no good reason. Revert the order of creation as we are going to depend on the pci_host_bridge structure to retrieve the domain number of the root bus. Signed-off-by: Liviu Dudau Acked-by: Grant Likely Tested-by: Tanmay Inamdar +-----------------------------------------------------------+------------+------------+ | | 003b5e6f33 | eef38aacf6 | +-----------------------------------------------------------+------------+------------+ | boot_successes | 0 | 0 | | boot_failures | 20 | 19 | | BUG:unable_to_handle_kernel_NULL_pointer_dereference | 20 | 19 | | Oops:SMP | 20 | 19 | | RIP:pcibios_root_bridge_prepare | 20 | 19 | | Kernel_panic-not_syncing:Attempted_to_kill_init_exitcode= | 20 | 19 | | backtrace:acpi_bus_scan | 20 | 19 | | backtrace:acpi_scan_init | 20 | 19 | | backtrace:acpi_init | 20 | 19 | | backtrace:kernel_init_freeable | 20 | 19 | +-----------------------------------------------------------+------------+------------+ [ 0.886041] acpi PNP0A03:00: _OSC: OS supports [Segments MSI] [ 0.888121] acpi PNP0A03:00: _OSC failed (AE_NOT_FOUND); disabling ASPM [ 0.895383] acpi PNP0A03:00: fail to add MMCONFIG information, can't access extended PCI configuration space under this bridge. [ 0.896026] BUG: unable to handle kernel NULL pointer dereference at 00000000000000c8 [ 0.897000] IP: [] pcibios_root_bridge_prepare+0x11/0x26 [ 0.897000] PGD 0 [ 0.897000] Oops: 0000 [#1] SMP [ 0.897000] Modules linked in: [ 0.897000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc2-00030-g003b5e6 #712 [ 0.897000] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 0.897000] task: ffff88001e6c8000 ti: ffff88001e6c4000 task.ti: ffff88001e6c4000 [ 0.897000] RIP: 0010:[] [] pcibios_root_bridge_prepare+0x11/0x26 [ 0.897000] RSP: 0000:ffff88001e6c5c00 EFLAGS: 00010282 [ 0.897000] RAX: 0000000000000000 RBX: ffff88001de68ee8 RCX: 0000000000000000 [ 0.897000] RDX: 0000000000000498 RSI: ffff88001e6c87f0 RDI: ffff88001dfe5cd0 [ 0.897000] RBP: ffff88001e6c5c90 R08: 00000000b0fa9e28 R09: 0000000000000001 [ 0.897000] R10: 000000000000a1e0 R11: 0000000000000000 R12: ffff88001dfe5cd0 [ 0.897000] R13: ffff88001de68f18 R14: 0000000000000000 R15: ffffffff821b1270 [ 0.897000] FS: 0000000000000000(0000) GS:ffff88001ea00000(0000) knlGS:0000000000000000 [ 0.897000] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 0.897000] CR2: 00000000000000c8 CR3: 00000000020ae000 CR4: 00000000000006f0 [ 0.897000] Stack: [ 0.897000] ffffffff814b15dc ffff88001dfe6148 ffff88001e428000 ffff88001e6c5cc8 [ 0.897000] 0000000000000000 ffff88001e6c5c90 ffffffff815f10ea ffffffff82026a3d [ 0.897000] ffff88001e6c5c48 ffff880000000010 ffff88001e6c5ca0 ffff88001e6c5c60 [ 0.897000] Call Trace: [ 0.897000] [] ? pci_create_root_bus+0x7e/0x31e [ 0.897000] [] ? dev_warn+0x5c/0x5e [ 0.897000] [] ? pci_mmconfig_insert+0xb2/0x1d0 [ 0.897000] [] pci_acpi_scan_root+0x30c/0x3aa [ 0.897000] [] acpi_pci_root_add+0x25b/0x32f [ 0.897000] [] acpi_bus_attach+0x85/0xf4 [ 0.897000] [] acpi_bus_attach+0xe1/0xf4 [ 0.897000] [] acpi_bus_attach+0xe1/0xf4 [ 0.897000] [] acpi_bus_scan+0x5b/0x6b [ 0.897000] [] ? acpi_sleep_proc_init+0x2a/0x2a [ 0.897000] [] acpi_scan_init+0x60/0x18e [ 0.897000] [] ? acpi_sleep_proc_init+0x2a/0x2a [ 0.897000] [] acpi_init+0x23f/0x257 [ 0.897000] [] do_one_initcall+0x84/0x11a [ 0.897000] [] ? parse_args+0x189/0x249 [ 0.897000] [] kernel_init_freeable+0x1d8/0x25d [ 0.897000] [] ? do_early_param+0x88/0x88 [ 0.897000] [] ? rest_init+0xcd/0xcd [ 0.897000] [] kernel_init+0xe/0xda [ 0.897000] [] ret_from_fork+0x7c/0xb0 [ 0.897000] [] ? rest_init+0xcd/0xcd [ 0.897000] Code: 71 b0 ff 48 8b 1b eb ee 48 83 c4 38 4c 89 e8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00 48 8b 87 70 04 00 00 55 48 89 e5 5d <48> 8b 80 c8 00 00 00 48 8b 40 08 48 89 87 c0 03 00 00 31 c0 c3 [ 0.897000] RIP [] pcibios_root_bridge_prepare+0x11/0x26 [ 0.897000] RSP [ 0.897000] CR2: 00000000000000c8 [ 0.897000] ---[ end trace 6110a1dd1810ff29 ]--- [ 0.897033] swapper/0 (1) used greatest stack depth: 3816 bytes left git bisect start eef38aacf67aae8b10c07c8b55b3f0fee627c8fa a79528e9d849803457b6235ddb1a1cfd4e11c6cd -- git bisect good f22b3e5788b29311219620adeb3edac565881241 # 09:02 20+ 0 dts: versatile: add pci controller binding git bisect bad 36623599ba01b3aba32c615a210ce50e195204fa # 09:04 0- 20 pci: Export find_pci_host_bridge() function. git bisect good d5bb25094600d096be062f823109753c6b218400 # 09:12 20+ 0 pci: OF: Fix the conversion of IO ranges into IO resources. git bisect bad 003b5e6f33242288b3da627ac8a9fffdc61067a0 # 09:19 0- 7 pci: Create pci_host_bridge before its associated bus in pci_create_root_bus. # first bad commit: [003b5e6f33242288b3da627ac8a9fffdc61067a0] pci: Create pci_host_bridge before its associated bus in pci_create_root_bus. git bisect good d5bb25094600d096be062f823109753c6b218400 # 09:26 60+ 0 pci: OF: Fix the conversion of IO ranges into IO resources. git bisect bad eef38aacf67aae8b10c07c8b55b3f0fee627c8fa # 09:26 0- 19 ARM: versatile: register sched_clock directly git bisect good f217c44ebd41ce7369d2df07622b2839479183b0 # 09:33 60+ 0 Merge tag 'trace-fixes-v3.14-rc7-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace git bisect good 9eee0105595d9d1f3702d0e8d8cf4950e400ed0b # 09:41 60+ 0 Add linux-next specific files for 20140327 This script may reproduce the error. ----------------------------------------------------------------------------- #!/bin/bash kernel=$1 kvm=( qemu-system-x86_64 -cpu kvm64 -enable-kvm -kernel $kernel -smp 2 -m 256M -net nic,vlan=0,macaddr=00:00:00:00:00:00,model=virtio -net user,vlan=0 -net nic,vlan=1,model=e1000 -net user,vlan=1 -boot order=nc -no-reboot -watchdog i6300esb -serial stdio -display none -monitor null ) append=( debug sched_debug apic=debug ignore_loglevel sysrq_always_enabled panic=10 prompt_ramdisk=0 earlyprintk=ttyS0,115200 console=ttyS0,115200 console=tty0 vga=normal root=/dev/ram0 rw ) "${kvm[@]}" --append "${append[*]}" ----------------------------------------------------------------------------- Thanks, Fengguang