Hi Kees, There are a number of oops that are bisect to commit 82fa9637a2ba285bcc7c5050c73010b2c1b3d803 ("x86, kaslr: Select random position from e820 maps"), unfortunately they are mostly hard to reproduce (often only 1 out of 100 boots is bad). However this one is very reproducible. I hope it can sever as a good case for debugging this issue. +------------------------------------------+------------+------------+---------------+ | | 5bfce5ef55 | 82fa9637a2 | next-20140919 | +------------------------------------------+------------+------------+---------------+ | boot_successes | 1000 | 6 | 49 | | boot_failures | 0 | 894 | 4 | | PANIC:early_exception | 0 | 894 | 2 | | BUG:kernel_boot_hang | 0 | 894 | 2 | | general_protection_fault | 0 | 0 | 1 | | RIP:__lock_acquire | 0 | 0 | 1 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 0 | 2 | | backtrace:free_reserved_area | 0 | 0 | 1 | | backtrace:free_init_pages | 0 | 0 | 1 | | backtrace:populate_rootfs | 0 | 0 | 1 | | backtrace:kernel_init_freeable | 0 | 0 | 1 | | backtrace:kvm_get_tsc_khz | 0 | 0 | 2 | | backtrace:kvmclock_init | 0 | 0 | 2 | | BUG:unable_to_handle_kernel | 0 | 0 | 1 | | Oops | 0 | 0 | 1 | | RIP:setup_real_mode | 0 | 0 | 1 | +------------------------------------------+------------+------------+---------------+ [ 0.000000] BRK [0x06bd4000, 0x06bd4fff] PGTABLE [ 0.000000] BRK [0x06bd5000, 0x06bd5fff] PGTABLE [ 0.000000] BRK [0x06bd6000, 0x06bd6fff] PGTABLE PANIC: early exception 0e rip 10:ffffffff842122df error 0 cr2 ffffffff829c9798 [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 3.12.0-rc4-00005-g82fa963 #1 PANIC: early exception 0e rip 10:ffffffff842126f6 error 0 cr2 ffffffff829c9798 BUG: kernel boot hang Elapsed time: 305 qemu-system-x86_64 -cpu kvm64 -enable-kvm -kernel /kernel/x86_64-randconfig-ib1-09191856/82fa9637a2ba285bcc7c5050c73010b2c1b3d803/vmlinuz-3.12.0-rc4-00005-g82fa963 -append 'hung_task_panic=1 earlyprintk=ttyS0,115200 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 root=/dev/ram0 rw link=/kbuild-tests/run-queue/kvm/x86_64-randconfig-ib1-09191856/next:master:82fa9637a2ba285bcc7c5050c73010b2c1b3d803:bisect-linux-5/.vmlinuz-82fa9637a2ba285bcc7c5050c73010b2c1b3d803-20140920200809-480-ivb41 branch=next/master BOOT_IMAGE=/kernel/x86_64-randconfig-ib1-09191856/82fa9637a2ba285bcc7c5050c73010b2c1b3d803/vmlinuz-3.12.0-rc4-00005-g82fa963 drbd.minor_count=8' -initrd /kernel-tests/initrd/yocto-minimal-x86_64.cgz -m 320 -smp 1 -net nic,vlan=1,model=e1000 -net user,vlan=1 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -pidfile /dev/shm/kboot/pid-yocto-ivb41-24 -serial file:/dev/shm/kboot/serial-yocto-ivb41-24 -daemonize -display none -monitor null git bisect start v3.14 v3.13 -- git bisect bad 494479038d97f1b9f76fc633a360a681acdf035c # 02:20 373- 19 Merge tag 'pinctrl-v3.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl git bisect bad 1b17366d695c8ab03f98d0155357e97a427e1dce # 02:33 310- 11 Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc git bisect bad 60eaa0190f6b39dce18eb1975d9773ed8bc9a534 # 02:44 153- 7 Merge tag 'trace-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace git bisect good 74e8ee8262c3f93bbc41804037b43f07b95897bb # 03:21 900+ 7 Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect bad 02d0a752460ea5dab34ce36c9ddc9c682e846a0d # 03:33 273- 8 Merge branch 'i2c/for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux git bisect bad 82b51734b4f228c76b6064b6e899d9d3d4c17c1a # 03:47 378- 16 Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux git bisect bad f4bcd8ccddb02833340652e9f46f5127828eb79d # 03:57 158- 1 Merge branch 'x86-kaslr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect good fab5669d556200c4dd119af705bff14085845d1e # 04:21 900+ 0 Merge branch 'x86-ras-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect good 7fe67a1180db49d41a3f764c379a08f8e31580ec # 05:31 900+ 4 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip git bisect bad 6145cfe394a7f138f6b64491c5663f97dba12450 # 05:50 3- 4 x86, kaslr: Raise the maximum virtual address to -1 GiB on x86_64 git bisect good 8ab3820fd5b2896d66da7bb2a906bc382e63e7bc # 20:01 900+ 0 x86, kaslr: Return location from decompress_kernel git bisect bad 82fa9637a2ba285bcc7c5050c73010b2c1b3d803 # 20:13 0- 32 x86, kaslr: Select random position from e820 maps git bisect good 5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3 # 22:04 900+ 0 x86, kaslr: Provide randomness functions # first bad commit: [82fa9637a2ba285bcc7c5050c73010b2c1b3d803] x86, kaslr: Select random position from e820 maps git bisect good 5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3 # 22:18 1000+ 0 x86, kaslr: Provide randomness functions git bisect bad 6a10bca9b608df445baa23c3bfafc510d93d425b # 22:31 0- 4 Add linux-next specific files for 20140919 git bisect bad 46be7b73e82453447cd97b3440d523159eab09f8 # 22:44 169- 13 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs git bisect bad 6a10bca9b608df445baa23c3bfafc510d93d425b # 22:44 0- 4 Add linux-next specific files for 20140919 This script may reproduce the error. ---------------------------------------------------------------------------- #!/bin/bash kernel=$1 kvm=( qemu-system-x86_64 -cpu kvm64 -enable-kvm -kernel $kernel -m 320 -smp 1 -net nic,vlan=1,model=e1000 -net user,vlan=1 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -serial stdio -display none -monitor null ) append=( hung_task_panic=1 earlyprintk=ttyS0,115200 debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 panic=-1 softlockup_panic=1 nmi_watchdog=panic oops=panic load_ramdisk=2 prompt_ramdisk=0 console=ttyS0,115200 console=tty0 vga=normal root=/dev/ram0 rw drbd.minor_count=8 ) "${kvm[@]}" --append "${append[*]}" ---------------------------------------------------------------------------- Thanks, Fengguang