FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git x86/uaccess commit 806ebc146567cb0030460ebf34ebecfb7c67eb76 ("[DEBUG] force CONFIG_DEBUG_UACCESS") on test machine: vm-lkp-wsx03-openwrt-i386: 1 threads qemu-system-i386 -enable-kvm with 192M memory caused below changes: +----------------------------------------------------+------------+------------+ | | 899f263944 | 806ebc1465 | +----------------------------------------------------+------------+------------+ | boot_successes | 6 | 0 | | boot_failures | 4 | 12 | | IP-Config:Auto-configuration_of_network_failed | 4 | | | BUG:tried_to_access_memory_at#while_not_in_USER_DS | 0 | 12 | | kernel_BUG_at_arch/x86/mm/extable.c | 0 | 12 | | invalid_opcode:#[##]SMP | 0 | 12 | | EIP_is_at_bad_uaccess_kernel_ds | 0 | 12 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 12 | | backtrace:do_vfs_ioctl | 0 | 6 | | backtrace:SyS_ioctl | 0 | 6 | | backtrace:do_execve | 0 | 2 | | backtrace:SyS_execve | 0 | 2 | +----------------------------------------------------+------------+------------+ [ 10.893589] Write protecting the kernel read-only data: 3932k procd: Console is alive procd: - watchdog - [ 10.922394] BUG: tried to access memory at 0x7ff6afd3 while not in USER_DS [ 10.922394] BUG: tried to access memory at 0x7ff6afd3 while not in USER_DS [ 10.923957] ------------[ cut here ]------------ [ 10.923957] ------------[ cut here ]------------ [ 10.924977] kernel BUG at arch/x86/mm/extable.c:189! [ 10.924977] kernel BUG at arch/x86/mm/extable.c:189! [ 10.926382] invalid opcode: 0000 [#1] SMP [ 10.926382] invalid opcode: 0000 [#1] SMP [ 10.927270] CPU: 0 PID: 1 Comm: init Not tainted 4.7.0-rc2-00014-g806ebc1 #403 [ 10.927270] CPU: 0 PID: 1 Comm: init Not tainted 4.7.0-rc2-00014-g806ebc1 #403 [ 10.928893] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 10.928893] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 10.930915] task: 8b440000 ti: 8b426000 task.ti: 8b426000 [ 10.930915] task: 8b440000 ti: 8b426000 task.ti: 8b426000 [ 10.932179] EIP: 0060:[<8102e631>] EFLAGS: 00010246 CPU: 0 [ 10.932179] EIP: 0060:[<8102e631>] EFLAGS: 00010246 CPU: 0 [ 10.933391] EIP is at bad_uaccess_kernel_ds+0xe/0x10 [ 10.933391] EIP is at bad_uaccess_kernel_ds+0xe/0x10 [ 10.934483] EAX: 0000003e EBX: 813de9b8 ECX: 81077607 EDX: 8b440000 [ 10.934483] EAX: 0000003e EBX: 813de9b8 ECX: 81077607 EDX: 8b440000 [ 10.935909] ESI: 7ff6afd0 EDI: fffffff7 EBP: 8b427ef8 ESP: 8b427ef0 [ 10.935909] ESI: 7ff6afd0 EDI: fffffff7 EBP: 8b427ef8 ESP: 8b427ef0 [ 10.937353] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [ 10.937353] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [ 10.938552] CR0: 80050033 CR2: 7777bc60 CR3: 0087a000 CR4: 00000690 [ 10.938552] CR0: 80050033 CR2: 7777bc60 CR3: 0087a000 CR4: 00000690 [ 10.939936] Stack: [ 10.939936] Stack: [ 10.940386] 81a330a5 [ 10.940386] 81a330a5 7ff6afd3 7ff6afd3 8b427f08 8b427f08 813deab5 813deab5 813de9b8 813de9b8 899cb780 899cb780 8b427f14 8b427f14 810edd0a 810edd0a [ 10.942231] 899cb780 [ 10.942231] 899cb780 8b427f68 8b427f68 810ee465 810ee465 00000002 00000002 00002180 00002180 899cb3c8 899cb3c8 88d146a8 88d146a8 810e100b 810e100b [ 10.944062] 00000001 [ 10.944062] 00000001 00000000 00000000 00000000 00000000 899cb3c0 899cb3c0 00000014 00000014 0804a2a5 0804a2a5 8b427f60 8b427f60 810e1d7c 810e1d7c [ 10.945951] Call Trace: [ 10.945951] Call Trace: [ 10.946493] [<813deab5>] wafwdt_ioctl+0xfd/0x14a [ 10.946493] [<813deab5>] wafwdt_ioctl+0xfd/0x14a [ 10.947528] [<813de9b8>] ? wafwdt_write+0x63/0x63 [ 10.947528] [<813de9b8>] ? wafwdt_write+0x63/0x63 [ 10.948611] [<810edd0a>] vfs_ioctl+0x17/0x21 [ 10.948611] [<810edd0a>] vfs_ioctl+0x17/0x21 [ 10.949568] [<810ee465>] do_vfs_ioctl+0x5bd/0x5ef [ 10.949568] [<810ee465>] do_vfs_ioctl+0x5bd/0x5ef [ 10.950620] [<810e100b>] ? fsnotify_modify+0x48/0x53 [ 10.950620] [<810e100b>] ? fsnotify_modify+0x48/0x53 [ 10.951781] [<810e1d7c>] ? vfs_write+0x9a/0xa6 [ 10.951781] [<810e1d7c>] ? vfs_write+0x9a/0xa6 [ 10.952781] [<810f61f6>] ? __fget_light+0x38/0x5a [ 10.952781] [<810f61f6>] ? __fget_light+0x38/0x5a [ 10.953909] [<810ee4c3>] SyS_ioctl+0x2c/0x45 [ 10.953909] [<810ee4c3>] SyS_ioctl+0x2c/0x45 [ 10.954866] [<81000d1c>] do_int80_syscall_32+0x48/0x5a [ 10.954866] [<81000d1c>] do_int80_syscall_32+0x48/0x5a [ 10.956055] [<8174d193>] entry_INT80_32+0x2f/0x2f [ 10.956055] [<8174d193>] entry_INT80_32+0x2f/0x2f [ 10.957100] Code: [ 10.957100] Code: 55 55 89 89 e5 e5 e8 e8 a0 a0 5e 5e 02 02 00 00 85 85 c0 c0 74 74 0d 0d 03 03 40 40 08 08 3d 3d 33 33 e4 e4 02 02 81 81 0f 0f 94 94 c0 c0 eb eb 02 02 31 31 c0 c0 5d 5d c3 c3 55 55 89 89 e5 e5 50 50 68 68 a5 a5 30 30 a3 a3 81 81 e8 e8 3a 3a 3b 3b 08 08 00 00 <0f> <0f> 0b 0b 55 55 89 89 e5 e5 57 57 56 56 53 53 53 53 89 89 c3 c3 8b 8b 40 40 30 30 89 89 d7 d7 89 89 4d 4d f0 f0 e8 e8 65 65 [ 10.962411] EIP: [<8102e631>] [ 10.962411] EIP: [<8102e631>] bad_uaccess_kernel_ds+0xe/0x10bad_uaccess_kernel_ds+0xe/0x10 SS:ESP 0068:8b427ef0 SS:ESP 0068:8b427ef0 [ 10.964179] ---[ end trace 69eab45c801d3298 ]--- [ 10.964179] ---[ end trace 69eab45c801d3298 ]--- FYI, raw QEMU command line is: qemu-system-i386 -enable-kvm -kernel /pkg/linux/i386-randconfig-n0-201624/gcc-6/806ebc146567cb0030460ebf34ebecfb7c67eb76/vmlinuz-4.7.0-rc2-00014-g806ebc1 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-lkp-wsx03-openwrt-i386-2/bisect_boot-1-openwrt-i386.cgz-i386-randconfig-n0-201624-806ebc146567cb0030460ebf34ebecfb7c67eb76-20160614-88421-7u28ig-0.yaml~ ARCH=i386 kconfig=i386-randconfig-n0-201624 branch=linux-devel/devel-catchup-201606141100 commit=806ebc146567cb0030460ebf34ebecfb7c67eb76 BOOT_IMAGE=/pkg/linux/i386-randconfig-n0-201624/gcc-6/806ebc146567cb0030460ebf34ebecfb7c67eb76/vmlinuz-4.7.0-rc2-00014-g806ebc1 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-lkp-wsx03-openwrt-i386/openwrt-i386.cgz/i386-randconfig-n0-201624/gcc-6/806ebc146567cb0030460ebf34ebecfb7c67eb76/0 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-openwrt-i386-2::dhcp drbd.minor_count=8' -initrd /fs/sdc1/initrd-vm-lkp-wsx03-openwrt-i386-2 -m 192 -smp 1 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -drive file=/fs/sdc1/disk0-vm-lkp-wsx03-openwrt-i386-2,media=disk,if=virtio -drive file=/fs/sdc1/disk1-vm-lkp-wsx03-openwrt-i386-2,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-lkp-wsx03-openwrt-i386-2 -serial file:/dev/shm/kboot/serial-vm-lkp-wsx03-openwrt-i386-2 -daemonize -display none -monitor null Thanks, Kernel Test Robot