FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git x86/uaccess commit 4805ee99b0ac1282d09545e294e218a575208b72 ("[DEBUG] force CONFIG_DEBUG_UACCESS") on test machine: vm-lkp-wsx03-quantal-i386: 1 threads qemu-system-i386 -enable-kvm with 360M memory caused below changes: +----------------+------------+------------+ | | 19cca1fd38 | 4805ee99b0 | +----------------+------------+------------+ | boot_successes | 26 | 0 | +----------------+------------+------------+ [ 27.685036] Write protecting the kernel text: 7112k [ 27.695139] Write protecting the kernel read-only data: 2544k [ 27.722178] random: init urandom read with 1 bits of entropy available [ 27.795802] BUG: tried to access memory at 0x9eaf48b while not in USER_DS [ 27.806808] BUG: tried to access memory at 0x94a52ab while not in USER_DS [ 27.806837] ------------[ cut here ]------------ [ 27.806840] kernel BUG at arch/x86/mm/extable.c:189! [ 27.806843] invalid opcode: 0000 [#1] SMP [ 27.806847] Modules linked in: [ 27.806859] CPU: 0 PID: 131 Comm: sh Not tainted 4.7.0-rc2-00014-g4805ee9 #1 [ 27.806861] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014 [ 27.806864] task: ccb1b480 ti: d625e000 task.ti: d625e000 [ 27.806874] EIP: 0060:[<c1045626>] EFLAGS: 00010292 CPU: 0 [ 27.806904] EIP is at bad_uaccess_kernel_ds+0x16/0x20 [ 27.806907] EAX: 0000003d EBX: 094a52a8 ECX: c10a20ae EDX: 00000001 [ 27.806908] ESI: 00000000 EDI: ccb1b480 EBP: d625ff24 ESP: d625ff1c [ 27.806910] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [ 27.806912] CR0: 80050033 CR2: 094a5000 CR3: 1625a000 CR4: 00000690 [ 27.806918] Stack: [ 27.806926] c18acd14 094a52ab d625ff38 c1175ad6 00000000 d5e75c00 ccaeb000 d625ff74 [ 27.806932] c11774a0 00000002 00000000 00000000 c11771a6 d62492bc 00000000 d5e75c00 [ 27.806939] 094a52a8 d62c76c0 00000000 d625ffb4 d625e000 b771aff4 d625ff84 c11779eb [ 27.806940] Call Trace: [ 27.806964] [<c1175ad6>] count+0x36/0xc0 [ 27.806969] [<c11774a0>] do_execveat_common+0x3e0/0x6c0 [ 27.806974] [<c11771a6>] ? do_execveat_common+0xe6/0x6c0 [ 27.806978] [<c11779eb>] SyS_execve+0x2b/0x30 [ 27.806982] [<c10014bd>] do_int80_syscall_32+0x6d/0xc0 [ 27.807005] [<c16eff5a>] entry_INT80_32+0x2a/0x2a [ 27.807050] Code: 26 00 00 00 00 31 c0 5d c3 8d b6 00 00 00 00 8d bf 00 00 00 00 55 89 e5 83 ec 08 89 44 24 04 c7 04 24 14 cd 8a c1 e8 09 b4 0d 00 <0f> 0b 90 8d b4 26 00 00 00 00 55 89 e5 57 56 53 83 ec 0c 89 c3 [ 27.807057] EIP: [<c1045626>] bad_uaccess_kernel_ds+0x16/0x20 SS:ESP 0068:d625ff1c [ 27.807081] ---[ end trace ecc4b7edb5ca4295 ]--- [ 27.807084] Kernel panic - not syncing: Fatal exception FYI, raw QEMU command line is: qemu-system-i386 -enable-kvm -kernel /pkg/linux/i386-randconfig-r0-201623/gcc-6/4805ee99b0ac1282d09545e294e218a575208b72/vmlinuz-4.7.0-rc2-00014-g4805ee9 -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-lkp-wsx03-quantal-i386-11/bisect_boot-1-quantal-core-i386.cgz-i386-randconfig-r0-201623-4805ee99b0ac1282d09545e294e218a575208b72-20160611-75443-cg68q1-1.yaml~ ARCH=i386 kconfig=i386-randconfig-r0-201623 branch=linux-devel/devel-catchup-201606110618 commit=4805ee99b0ac1282d09545e294e218a575208b72 BOOT_IMAGE=/pkg/linux/i386-randconfig-r0-201623/gcc-6/4805ee99b0ac1282d09545e294e218a575208b72/vmlinuz-4.7.0-rc2-00014-g4805ee9 max_uptime=600 RESULT_ROOT=/result/boot/1/vm-lkp-wsx03-quantal-i386/quantal-core-i386.cgz/i386-randconfig-r0-201623/gcc-6/4805ee99b0ac1282d09545e294e218a575208b72/0 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-i386-11::dhcp drbd.minor_count=8' -initrd /fs/sdc1/initrd-vm-lkp-wsx03-quantal-i386-11 -m 360 -smp 1 -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-i386-11 -serial file:/dev/shm/kboot/serial-vm-lkp-wsx03-quantal-i386-11 -daemonize -display none -monitor null Thanks, Kernel Test Robot