Greeting, FYI, we noticed the following commit (built with clang-15): commit: 3aeaac747d194aa3cff28351b4a83267faa11b3a ("[PATCH v7] timekeeping: Add raw clock fallback for random_get_entropy()") url: https://github.com/intel-lab-lkp/linux/commits/Jason-A-Donenfeld/timekeeping-Add-raw-clock-fallback-for-random_get_entropy/20220505-082221 base: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git 107c948d1d3e61d10aee9d0f7c3d81bbee9842af patch link: https://lore.kernel.org/lkml/20220505001924.176087-1-Jason@zx2c4.com in testcase: boot 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): +---------------------------------+------------+------------+ | | 107c948d1d | 3aeaac747d | +---------------------------------+------------+------------+ | boot_successes | 14 | 0 | | boot_failures | 0 | 12 | | PANIC:early_exception | 0 | 12 | | RIP:random_get_entropy_fallback | 0 | 12 | | BUG:kernel_hang_in_boot_stage | 0 | 12 | +---------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 0.000000][ T0] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved [ 0.000000][ T0] BIOS-e820: [mem 0x0000000100000000-0x000000043fffffff] usable [ 0.000000][ T0] printk: debug: ignoring loglevel setting. [ 0.000000][ T0] printk: bootconsole [earlyser0] enabled [ 0.000000][ T0] NX (Execute Disable) protection: active PANIC: early exception 0x0d IP 10:ffffffff812cef11 error 0 cr2 0xffff888004a3aff8 [ 0.000000][ T0] CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0-rc5-00017-g3aeaac747d19 #4 [ 0.000000][ T0] RIP: 0010:random_get_entropy_fallback (kbuild/src/rand-3/kernel/time/timekeeping.c:194 kbuild/src/rand-3/kernel/time/timekeeping.c:2390) [ 0.000000][ T0] Code: 41 5d 41 5e 41 5f 5d c3 90 f3 0f 1e fa 55 48 89 e5 53 48 8b 1d 00 4e df 03 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 48 89 df e8 d1 2f 3b 00 4c 8b 1b 48 89 df e8 f6 All code ======== 0: 41 5d pop %r13 2: 41 5e pop %r14 4: 41 5f pop %r15 6: 5d pop %rbp 7: c3 retq 8: 90 nop 9: f3 0f 1e fa endbr64 d: 55 push %rbp e: 48 89 e5 mov %rsp,%rbp 11: 53 push %rbx 12: 48 8b 1d 00 4e df 03 mov 0x3df4e00(%rip),%rbx # 0x3df4e19 19: 48 89 d8 mov %rbx,%rax 1c: 48 c1 e8 03 shr $0x3,%rax 20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 27: fc ff df 2a:* 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction 2e: 74 08 je 0x38 30: 48 89 df mov %rbx,%rdi 33: e8 d1 2f 3b 00 callq 0x3b3009 38: 4c 8b 1b mov (%rbx),%r11 3b: 48 89 df mov %rbx,%rdi 3e: e8 .byte 0xe8 3f: f6 .byte 0xf6 Code starting with the faulting instruction =========================================== 0: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) 4: 74 08 je 0xe 6: 48 89 df mov %rbx,%rdi 9: e8 d1 2f 3b 00 callq 0x3b2fdf e: 4c 8b 1b mov (%rbx),%r11 11: 48 89 df mov %rbx,%rdi 14: e8 .byte 0xe8 15: f6 .byte 0xf6 [ 0.000000][ T0] RSP: 0000:ffffffff84a07d70 EFLAGS: 00010046 ORIG_RAX: 0000000000000000 [ 0.000000][ T0] RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 0.000000][ T0] RDX: ffffffffff240a7a RSI: 00000000000001da RDI: ffffffffff2408a0 [ 0.000000][ T0] RBP: ffffffff84a07d78 R08: 0000000000dbf764 R09: 000000000000000b [ 0.000000][ T0] R10: ffffffff86a00070 R11: ffffffff8583df04 R12: dffffc0000000000 [ 0.000000][ T0] R13: ffffffff84a07e50 R14: ffffffffff2408a0 R15: 00000000000001da [ 0.000000][ T0] FS: 0000000000000000(0000) GS:ffffffff84a9e000(0000) knlGS:0000000000000000 [ 0.000000][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.000000][ T0] CR2: ffff888004a3aff8 CR3: 0000000005876000 CR4: 00000000000406a0 [ 0.000000][ T0] Call Trace: [ 0.000000][ T0] [ 0.000000][ T0] add_device_randomness (kbuild/src/rand-3/drivers/char/random.c:1028) [ 0.000000][ T0] ? dmi_walk_early (kbuild/src/rand-3/drivers/firmware/dmi_scan.c:470) [ 0.000000][ T0] dmi_walk_early (kbuild/src/rand-3/drivers/firmware/dmi_scan.c:151) [ 0.000000][ T0] dmi_present (kbuild/src/rand-3/drivers/firmware/dmi_scan.c:605) To reproduce: # build kernel cd linux cp config-5.18.0-rc5-00017-g3aeaac747d19 .config make HOSTCC=clang-15 CC=clang-15 ARCH=x86_64 olddefconfig prepare modules_prepare bzImage modules make HOSTCC=clang-15 CC=clang-15 ARCH=x86_64 INSTALL_MOD_PATH= modules_install cd find lib/ | cpio -o -H newc --quiet | gzip > modules.cgz 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 # if come across any failure that blocks the test, # please remove ~/.lkp and /lkp dir to run from a clean state. -- 0-DAY CI Kernel Test Service https://01.org/lkp