Greeting, FYI, we noticed the following commit (built with gcc-9): commit: f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674 ("sched/core: Initialize the idle task with preemption disabled") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master in testcase: locktorture version: with following parameters: runtime: 300s test: cpuhotplug test-description: This torture test consists of creating a number of kernel threads which acquire the lock and hold it for specific amount of time, thus simulating different critical region behaviors. test-url: https://www.kernel.org/doc/Documentation/locking/locktorture.txt on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 227.905035] BUG: KASAN: stack-out-of-bounds in vsnprintf+0x1823/0x1a80 [ 227.905062] Read of size 8 at addr ffffc9000010ff00 by task swapper/1/0 [ 227.905084] [ 227.905102] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.13.0-rc1-00108-gf1a0a376ca0c #1 [ 227.905133] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 227.905157] Call Trace: [ 227.905171] dump_stack+0x198/0x247 [ 227.905190] print_address_description.cold+0x5/0x32d [ 227.905212] ? vsnprintf+0x1823/0x1a80 [ 227.905229] kasan_report.cold+0x7c/0xd8 [ 227.905246] ? vsnprintf+0x1823/0x1a80 [ 227.905263] vsnprintf+0x1823/0x1a80 [ 227.905279] ? pointer+0x780/0x780 [ 227.905295] ? sched_clock_cpu+0x38/0x220 [ 227.905312] vprintk_store+0x14d/0xa80 [ 227.905330] ? __ia32_sys_syslog+0xc0/0xc0 [ 227.905348] ? ftrace_likely_update+0xa4/0x180 [ 227.905367] ? pvclock_clocksource_read+0x2dd/0x5a0 [ 227.905386] ? write_comp_data+0x2a/0x80 [ 227.905404] ? __sanitizer_cov_trace_pc+0x1d/0x60 [ 227.905423] vprintk_emit+0x144/0x600 [ 227.905439] vprintk+0xac/0x1e0 [ 227.905453] printk+0xa3/0xc1 [ 227.905470] ? stress_reorder_work.cold+0x2a/0x2a [ 227.905489] ? slow_virt_to_phys+0x15b/0x340 [ 227.905507] ? ftrace_likely_update+0xa4/0x180 [ 227.905526] start_secondary+0x4a/0x280 [ 227.905544] secondary_startup_64_no_verify+0xb0/0xbb [ 227.905561] [ 227.905572] [ 227.905592] addr ffffc9000010ff00 is located in stack of task swapper/1/0 at offset 120 in frame: [ 227.905619] printk+0x0/0xc1 [ 227.905633] [ 227.905646] this frame has 1 object: [ 227.905664] [32, 56) 'args' [ 227.905678] [ 227.905694] Memory state around the buggy address: [ 227.905718] ffffc9000010fe00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 227.905746] ffffc9000010fe80: 00 f1 f1 f1 f1 00 00 00 f3 f3 f3 f3 f3 00 00 00 [ 227.905775] >ffffc9000010ff00: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 227.905799] ^ [ 227.905820] ffffc9000010ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 [ 227.905848] ffffc90000110000: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 [ 227.905876] ================================================================== [ 227.905902] Disabling lock debugging due to kernel taint [ 227.974158] smpboot: CPU 1 is now offline [ 231.067528] x86: Booting SMP configuration: [ 231.068838] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 231.090360] kvm-clock: cpu 1, msr 8a01041, secondary cpu clock [ 231.090509] masked ExtINT on CPU#1 [ 231.117328] kvm-guest: stealtime: cpu 1, msr 3aebf8080 [ 237.501337] smpboot: CPU 1 is now offline [ 240.667721] x86: Booting SMP configuration: [ 240.669915] smpboot: Booting Node 0 Processor 1 APIC 0x1 [ 240.672831] kvm-clock: cpu 1, msr 8a01041, secondary cpu clock [ 240.672991] masked ExtINT on CPU#1 [ 240.713721] kvm-guest: stealtime: cpu 1, msr 3aebf8080 Kboot worker: lkp-worker51 Elapsed time: 240 kvm=( qemu-system-x86_64 -enable-kvm -cpu SandyBridge -kernel $kernel -initrd initrd-vm-snb-228.cgz -m 16384 -smp 2 -device e1000,netdev=net0 -netdev user,id=net0,hostfwd=tcp::32032-:22 -boot order=nc -no-reboot -watchdog i6300esb -watchdog-action debug -rtc base=localtime -serial stdio -display none -monitor null ) append=( ip=::::vm-snb-228::dhcp root=/dev/ram0 user=lkp job=/job-script ARCH=x86_64 kconfig=x86_64-randconfig-a014-20210513 branch=tip/sched/core commit=f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674 BOOT_IMAGE=/pkg/linux/x86_64-randconfig-a014-20210513/gcc-9/f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674/vmlinuz-5.13.0-rc1-00108-gf1a0a376ca0c vmalloc=512M max_uptime=2100 RESULT_ROOT=/result/locktorture/300s-cpuhotplug/vm-snb/debian-10.4-x86_64-20200603.cgz/x86_64-randconfig-a014-20210513/gcc-9/f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674/21 result_service=tmpfs selinux=0 debug apic=debug sysrq_always_enabled rcupdate.rcu_cpu_stall_timeout=100 net.ifnames=0 To reproduce: git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k -m modules.cgz job-script # job-script is attached in this email --- 0DAY/LKP+ Test Infrastructure Open Source Technology Center https://lists.01.org/hyperkitty/list/lkp@lists.01.org Intel Corporation Thanks, Oliver Sang