FYI, we noticed the following commit: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git x86/vmap_stack commit 325e2efd8c4ae6b4bf328e0ede2acfe8b3b48e79 ("sched: Free the stack early if CONFIG_THREAD_INFO_IN_TASK") in testcase: boot on test machine: 1 threads qemu-system-x86_64 -enable-kvm -cpu Westmere with 320M memory caused below changes: +--------------------------------------------------------------+------------+------------+ | | 7117d60112 | 325e2efd8c | +--------------------------------------------------------------+------------+------------+ | boot_successes | 91 | 1 | | boot_failures | 9 | 30 | | Out_of_memory:Kill_process | 4 | | | BUG:kernel_test_oversize | 4 | | | WARNING:at_arch/x86/include/asm/fpu/internal.h:#fpu__restore | 1 | | | BUG:unable_to_handle_kernel | 0 | 30 | | Oops | 0 | 30 | | RIP:do_raw_spin_lock | 0 | 30 | | Kernel_panic-not_syncing:Fatal_exception | 0 | 30 | | backtrace:kthread_stop | 0 | 30 | | backtrace:test_rht_init | 0 | 30 | | backtrace:kernel_init_freeable | 0 | 30 | +--------------------------------------------------------------+------------+------------+ [ 1.603591] Test failed: thread 6 returned: -12 [ 1.603595] Test failed: thread 7 returned: -12 [ 1.631305] Test failed: thread 8 returned: -12 [ 1.632027] BUG: unable to handle kernel paging request at ffff88000ea0befc [ 1.633135] IP: [<ffffffff8111599a>] do_raw_spin_lock+0x2a/0x120 [ 1.634101] PGD 55e1067 PUD 55e2067 PMD 1398b067 PTE 800000000ea0b060 [ 1.635199] Oops: 0000 [#1] PREEMPT DEBUG_PAGEALLOC [ 1.635935] CPU: 0 PID: 1 Comm: swapper Not tainted 4.7.0-rc4-00256-g325e2ef #2 [ 1.637047] task: ffff880013552600 task.stack: ffff880013558000 [ 1.637979] RIP: 0010:[<ffffffff8111599a>] [<ffffffff8111599a>] do_raw_spin_lock+0x2a/0x120 [ 1.639304] RSP: 0000:ffff88001355bd18 EFLAGS: 00010082 [ 1.640118] RAX: 0000000000000000 RBX: ffff88000ea0bef8 RCX: 0000000000000000 [ 1.641206] RDX: 0000000000000000 RSI: 00000000000005a8 RDI: ffff88000ea0bef8 [ 1.642294] RBP: ffff88001355bd30 R08: 0000000000001000 R09: 0000000000000002 [ 1.643376] R10: 0000000000000067 R11: 00003ffffffff000 R12: ffff88000ea0bef8 [ 1.644453] R13: ffff88000ea0bef0 R14: ffff880013552600 R15: ffff880013552600 [ 1.645539] FS: 0000000000000000(0000) GS:ffffffff8304c000(0000) knlGS:0000000000000000 [ 1.646755] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.647647] CR2: ffff88000ea0befc CR3: 000000000300c000 CR4: 00000000000006b0 [ 1.648718] Stack: [ 1.649055] ffff88000ea0bef8 ffff88000ea0bef8 ffff88000ea0bef0 ffff88001355bd48 [ 1.650269] ffffffff82793ca1 7fffffffffffffff ffff88001355bdb0 ffffffff8278ecf3 [ 1.651467] ffff88001355bd78 0000000000000001 ffff880013552600 ffffffff811007b0 [ 1.652679] Call Trace: [ 1.653048] [<ffffffff82793ca1>] _raw_spin_lock_irq+0x21/0x30 [ 1.653944] [<ffffffff8278ecf3>] wait_for_completion+0x133/0x1c0 [ 1.654887] [<ffffffff811007b0>] ? sched_set_stop_task+0x60/0x60 [ 1.655807] [<ffffffff810f801b>] kthread_stop+0x5b/0xa0 [ 1.656623] [<ffffffff8449d644>] test_rht_init+0xa87/0xb40 [ 1.657476] [<ffffffff8449cbbd>] ? test_kstrtox_init+0xb9b/0xb9b [ 1.658454] [<ffffffff8446b454>] do_one_initcall+0xd1/0x164 [ 1.659328] [<ffffffff8446b71b>] kernel_init_freeable+0x234/0x2ff [ 1.660288] [<ffffffff827843da>] kernel_init+0xa/0x110 [ 1.661047] [<ffffffff8279449d>] ret_from_fork+0x1d/0x40 [ 1.661869] [<ffffffff827843d0>] ? rest_init+0x80/0x80 [ 1.662667] Code: 00 55 48 89 e5 48 83 ec 18 48 85 ff 48 89 5d e8 4c 89 65 f0 48 89 fb 4c 89 6d f8 75 0e 31 f6 48 c7 c7 c0 8b 0d 83 e8 a6 dd 69 00 <81> 7b 04 ad 4e ad de 74 18 e8 a8 37 63 00 85 c0 74 0f 48 c7 c6 [ 1.666891] RIP [<ffffffff8111599a>] do_raw_spin_lock+0x2a/0x120 [ 1.667830] RSP <ffff88001355bd18> [ 1.668391] CR2: ffff88000ea0befc [ 1.668904] ---[ end trace fdce1905cee5a7a0 ]--- [ 1.669633] Kernel panic - not syncing: Fatal exception FYI, raw QEMU command line is: qemu-system-x86_64 -enable-kvm -cpu Westmere -kernel /pkg/linux/x86_64-randconfig-s4-06300257/gcc-6/325e2efd8c4ae6b4bf328e0ede2acfe8b3b48e79/vmlinuz-4.7.0-rc4-00256-g325e2ef -append 'root=/dev/ram0 user=lkp job=/lkp/scheduled/vm-kbuild-yocto-ia32-28/bisect_boot-1-yocto-minimal-i386.cgz-x86_64-randconfig-s4-06300257-325e2efd8c4ae6b4bf328e0ede2acfe8b3b48e79-20160630-98844-15a2z12-0.yaml ARCH=x86_64 kconfig=x86_64-randconfig-s4-06300257 branch=linux-devel/devel-spot-201606300239 commit=325e2efd8c4ae6b4bf328e0ede2acfe8b3b48e79 BOOT_IMAGE=/pkg/linux/x86_64-randconfig-s4-06300257/gcc-6/325e2efd8c4ae6b4bf328e0ede2acfe8b3b48e79/vmlinuz-4.7.0-rc4-00256-g325e2ef max_uptime=600 RESULT_ROOT=/result/boot/1/vm-kbuild-yocto-ia32/yocto-minimal-i386.cgz/x86_64-randconfig-s4-06300257/gcc-6/325e2efd8c4ae6b4bf328e0ede2acfe8b3b48e79/0 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-kbuild-yocto-ia32-28::dhcp drbd.minor_count=8' -initrd /fs/sdg1/initrd-vm-kbuild-yocto-ia32-28 -m 320 -smp 1 -device e1000,netdev=net0 -netdev user,id=net0 -boot order=nc -no-reboot -watchdog i6300esb -rtc base=localtime -drive file=/fs/sdg1/disk0-vm-kbuild-yocto-ia32-28,media=disk,if=virtio -pidfile /dev/shm/kboot/pid-vm-kbuild-yocto-ia32-28 -serial file:/dev/shm/kboot/serial-vm-kbuild-yocto-ia32-28 -daemonize -display none -monitor null Thanks, Xiaolong