Greeting, FYI, we noticed the following commit (built with gcc-9): commit: 54b35bdb5a110e86e605e25c071ee34431be06bb ("fs: honor LOOKUP_NONBLOCK for the last part of file open") https://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git nonblock-path-lookup in testcase: boot on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 8G caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace): +---------------------------------------------+------------+------------+ | | cae472f634 | 54b35bdb5a | +---------------------------------------------+------------+------------+ | boot_successes | 6 | 0 | | boot_failures | 0 | 20 | | WARNING:possible_recursive_locking_detected | 0 | 20 | | BUG:kernel_hang_in_boot_stage | 0 | 20 | +---------------------------------------------+------------+------------+ If you fix the issue, kindly add following tag Reported-by: kernel test robot [ 1.820362] WARNING: possible recursive locking detected [ 1.821377] 5.10.0-rc7-00093-g54b35bdb5a11 #1 Not tainted [ 1.821606] -------------------------------------------- [ 1.821606] swapper/1 is trying to acquire lock: [ 1.821606] 41e76e18 (&sb->s_type->i_mutex_key){++++}-{3:3}, at: walk_component+0xdd/0x160 [ 1.821606] [ 1.821606] but task is already holding lock: [ 1.821606] 41e76e18 (&sb->s_type->i_mutex_key){++++}-{3:3}, at: path_openat+0x206/0x940 [ 1.821606] [ 1.821606] other info that might help us debug this: [ 1.821606] Possible unsafe locking scenario: [ 1.821606] [ 1.821606] CPU0 [ 1.821606] ---- [ 1.821606] lock(&sb->s_type->i_mutex_key); [ 1.821606] [ 1.821606] *** DEADLOCK *** [ 1.821606] [ 1.821606] May be due to missing lock nesting notation [ 1.821606] [ 1.821606] 1 lock held by swapper/1: [ 1.821606] #0: 41e76e18 (&sb->s_type->i_mutex_key){++++}-{3:3}, at: path_openat+0x206/0x940 [ 1.821606] [ 1.821606] stack backtrace: [ 1.821606] CPU: 0 PID: 1 Comm: swapper Not tainted 5.10.0-rc7-00093-g54b35bdb5a11 #1 [ 1.821606] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 [ 1.821606] Call Trace: [ 1.821606] ? dump_stack+0x1b/0x1d [ 1.821606] ? validate_chain.cold+0x12a/0x135 [ 1.821606] ? __lock_acquire+0x48d/0x980 [ 1.821606] ? lock_acquire+0x97/0x280 [ 1.821606] ? walk_component+0xdd/0x160 [ 1.821606] ? down_read+0x32/0x100 [ 1.821606] ? walk_component+0xdd/0x160 [ 1.821606] ? path_lookupat+0x56/0x120 [ 1.821606] ? filename_lookup+0x6e/0x100 [ 1.821606] ? rcu_read_lock_sched_held+0x1b/0x40 [ 1.821606] ? kern_path+0x1f/0x40 [ 1.821606] ? init_stat+0x20/0x51 [ 1.821606] ? clean_path+0x1c/0x4e [ 1.821606] ? simple_strtoull+0x22/0x40 [ 1.821606] ? simple_strtoul+0x8/0x20 [ 1.821606] ? do_header+0x86/0x1f4 [ 1.821606] ? do_symlink+0x27/0x88 [ 1.821606] ? write_buffer+0x1f/0x2e [ 1.821606] ? flush_buffer+0x21/0x6f [ 1.821606] ? __gunzip+0x20f/0x299 [ 1.821606] ? decompress_method+0x66/0x66 [ 1.821606] ? __gunzip+0x299/0x299 [ 1.821606] ? gunzip+0x16/0x18 [ 1.821606] ? write_buffer+0x2e/0x2e [ 1.821606] ? initrd_load+0x38/0x38 [ 1.821606] ? unpack_to_rootfs+0x166/0x26b [ 1.821606] ? write_buffer+0x2e/0x2e [ 1.821606] ? initrd_load+0x38/0x38 [ 1.821606] ? do_copy+0xca/0xca [ 1.821606] ? populate_rootfs+0x47/0x93 [ 1.821606] ? do_one_initcall+0x54/0x200 [ 1.821606] ? parse_args+0xe0/0x300 [ 1.821606] ? rcu_read_lock_sched_held+0x1b/0x40 [ 1.821606] ? trace_initcall_level+0x4d/0x74 [ 1.821606] ? kernel_init_freeable+0x112/0x181 [ 1.821606] ? kernel_init_freeable+0x137/0x181 [ 1.821606] ? rest_init+0xfb/0xfb [ 1.821606] ? kernel_init+0x8/0xe5 [ 1.821606] ? ret_from_fork+0x1c/0x28 BUG: kernel hang in boot stage To reproduce: # build kernel cd linux cp config-5.10.0-rc7-00093-g54b35bdb5a11 .config make HOSTCC=gcc-9 CC=gcc-9 ARCH=i386 olddefconfig prepare modules_prepare bzImage git clone https://github.com/intel/lkp-tests.git cd lkp-tests bin/lkp qemu -k job-script # job-script is attached in this email Thanks, Rong Chen