FYI, we noticed the following commit: git://git.infradead.org/users/willy/linux-dax.git idr-2016-04-25 commit dbb5d8f2adff4465b3ff4d9bae970e01f9eb7940 ("Reimplement IDR and IDA using the radix tree") on test machine: vm-lkp-wsx03-quantal-x86_64: 2 threads qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap with 360M memory caused below changes: +------------------------------------------+------------+------------+ | | 411ca2f674 | dbb5d8f2ad | +------------------------------------------+------------+------------+ | boot_successes | 6 | 0 | | boot_failures | 0 | 7 | | BUG:unable_to_handle_kernel | 0 | 7 | | Oops | 0 | 7 | | RIP:ida_simple_get | 0 | 7 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 7 | +------------------------------------------+------------+------------+ [ 0.144964] [ 0.145224] Mount-cache hash table entries: 1024 (order: 1, 8192 bytes) [ 0.146039] Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes) [ 0.146869] BUG: unable to handle kernel paging request at 0000000082403e5c [ 0.147696] IP: [<ffffffff813f3e0f>] ida_simple_get+0x69/0xae [ 0.148370] PGD 0 [ 0.148622] Oops: 0000 [#1] PREEMPT SMP [ 0.149097] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.6.0-rc2-00066-gdbb5d8f #1 [ 0.149954] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 0.150887] task: ffffffff82412500 ti: ffffffff82400000 task.ti: ffffffff82400000 [ 0.151683] RIP: 0010:[<ffffffff813f3e0f>] [<ffffffff813f3e0f>] ida_simple_get+0x69/0xae [ 0.152554] RSP: 0000:ffffffff82403e50 EFLAGS: 00010046 [ 0.153097] RAX: 0000000000000000 RBX: ffff8800000820d0 RCX: ffffffff82403e40 [ 0.154062] RDX: ffff8800000820d8 RSI: 0000000000000001 RDI: ffff8800000820d0 [ 0.154931] RBP: 0000000082403e88 R08: 0000000000000001 R09: 0000000000000037 [ 0.155814] R10: ffffffff82403e50 R11: 0000000000000000 R12: 0000000000000001 [ 0.156684] R13: 00000000024000c0 R14: 0000000080000000 R15: 0000000000000202 [ 0.157550] FS: 0000000000000000(0000) GS:ffff880013c00000(0000) knlGS:0000000000000000 [ 0.158599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.159294] CR2: 0000000082403e5c CR3: 000000000240b000 CR4: 00000000000006b0 [ 0.160177] Stack: [ 0.160443] 0000000000000000 ffffffff82403e88 ffff88000002f000 ffffffff8230ec72 [ 0.161418] ffff8800000820c0 0000000000000001 000000000000416d ffffffff82403ec0 [ 0.162443] ffffffff811ad167 ffff8800000820c0 fffffffffffffff4 0000000000000002 [ 0.163408] Call Trace: [ 0.163718] [<ffffffff811ad167>] ? __kernfs_new_node+0x5b/0xb7 [ 0.164443] [<ffffffff811ae874>] ? kernfs_create_root+0x7c/0xec [ 0.165174] [<ffffffff8277070a>] ? sysfs_init+0x13/0x51 [ 0.165894] [<ffffffff8276fbe4>] ? mnt_init+0xf6/0x1f8 [ 0.166552] [<ffffffff8276f934>] ? vfs_caches_init+0x5f/0x6b [ 0.167256] [<ffffffff8274beff>] ? start_kernel+0x47c/0x4da [ 0.167950] [<ffffffff8274b120>] ? early_idt_handler_array+0x120/0x120 [ 0.168756] [<ffffffff8274b2f6>] ? x86_64_start_reservations+0x2a/0x2c [ 0.169563] [<ffffffff8274b3de>] ? x86_64_start_kernel+0xe6/0xf3 [ 0.170357] Code: e8 bf 4a 00 00 85 c0 74 55 48 c7 c7 20 b9 45 82 e8 a0 48 89 00 48 8d 55 d4 44 89 e6 48 89 df 49 89 c7 e8 04 4b 00 00 85 c0 75 17 <8b> 45 d4 41 39 c6 73 0f 89 c6 48 89 df e8 16 4c 00 00 b8 e4 ff [ 0.173783] RIP [<ffffffff813f3e0f>] ida_simple_get+0x69/0xae [ 0.174520] RSP <ffffffff82403e50> [ 0.174946] CR2: 0000000082403e5c [ 0.175361] ---[ end trace f4b42fa6fb26a58c ]--- [ 0.175931] Kernel panic - not syncing: Fatal exception FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu Haswell,+smep,+smap -kernel /pkg/linux/x86_64-acpi-redef/gcc-5/dbb5d8f2adff4465b3ff4d9bae970e01f9eb7940/vmlinuz-4.6.0-rc2-00066-gdbb5d8f -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-lkp-wsx03-quantal-x86_64-1/bisect_boot-1-quantal-core-x86_64.cgz-x86_64-acpi-redef-dbb5d8f2adff4465b3ff4d9bae970e01f9eb7940-20160426-86997-t5gvxe-0.yaml ARCH=x86_64 kconfig=x86_64-acpi-redef branch=linux-devel/devel-catchup-201604260608 commit=dbb5d8f2adff4465b3ff4d9bae970e01f9eb7940 BOOT_IMAGE=/pkg/linux/x86_64-acpi-redef/gcc-5/dbb5d8f2adff4465b3ff4d9bae970e01f9eb7940/vmlinuz-4.6.0-rc2-00066-gdbb5d8f max_uptime=600 RESULT_ROOT=/result/boot/1/vm-lkp-wsx03-quantal-x86_64/quantal-core-x86_64.cgz/x86_64-acpi-redef/gcc-5/dbb5d8f2adff4465b3ff4d9bae970e01f9eb7940/0 LKP_SERVER=inn earlyprintk=ttyS0,115200 systemd.log_level=err debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal rw ip=::::vm-lkp-wsx03-quantal-x86_64-1::dhcp drbd.minor_count=8' -initrd /fs/sdc1/initrd-vm-lkp-wsx03-quantal-x86_64-1 -m 360 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -pidfile /dev/shm/kboot/pid-vm-lkp-wsx03-quantal-x86_64-1 -serial file:/dev/shm/kboot/serial-vm-lkp-wsx03-quantal-x86_64-1 -daemonize -display none -monitor null Thanks, Kernel Test Robot