====================================================== WARNING: possible circular locking dependency detected 6.1.28-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor731/4219 is trying to acquire lock: ffff8000156054d0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0x1c/0x38 kernel/jump_label.c:158 but task is already holding lock: ffff800015796d88 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x50/0x150 kernel/cgroup/legacy_freezer.c:111 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (freezer_mutex){+.+.}-{3:3}: __mutex_lock_common+0x190/0x21a0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 freezer_change_state kernel/cgroup/legacy_freezer.c:389 [inline] freezer_write+0xc4/0x43c kernel/cgroup/legacy_freezer.c:429 cgroup_file_write+0x258/0x5ac kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x334/0x48c fs/kernfs/file.c:330 call_write_iter include/linux/fs.h:2205 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x610/0x914 fs/read_write.c:584 ksys_write+0x15c/0x26c fs/read_write.c:637 __do_sys_write fs/read_write.c:649 [inline] __se_sys_write fs/read_write.c:646 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:646 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 -> #0 (cpu_hotplug_lock){++++}-{0:0}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x70/0x2bc kernel/cpu.c:310 static_key_slow_inc+0x1c/0x38 kernel/jump_label.c:158 freezer_css_online+0xbc/0x150 kernel/cgroup/legacy_freezer.c:117 online_css+0xc8/0x2b4 kernel/cgroup/cgroup.c:5476 css_create kernel/cgroup/cgroup.c:5547 [inline] cgroup_apply_control_enable+0x6d8/0x9ac kernel/cgroup/cgroup.c:3235 cgroup_mkdir+0x9b4/0xd50 kernel/cgroup/cgroup.c:5743 kernfs_iop_mkdir+0x114/0x160 fs/kernfs/dir.c:1196 vfs_mkdir+0x334/0x4e4 fs/namei.c:4036 do_mkdirat+0x20c/0x610 fs/namei.c:4061 __do_sys_mkdirat fs/namei.c:4076 [inline] __se_sys_mkdirat fs/namei.c:4074 [inline] __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4074 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(freezer_mutex); lock(cpu_hotplug_lock); lock(freezer_mutex); lock(cpu_hotplug_lock); *** DEADLOCK *** 4 locks held by syz-executor731/4219: #0: ffff0000d8730460 (sb_writers#9){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393 #1: ffff0000df7be9d0 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline] #1: ffff0000df7be9d0 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: filename_create+0x200/0x464 fs/namei.c:3807 #2: ffff80001578c4c8 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xf8/0x258 kernel/cgroup/cgroup.c:1667 #3: ffff800015796d88 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x50/0x150 kernel/cgroup/legacy_freezer.c:111 stack backtrace: CPU: 1 PID: 4219 Comm: syz-executor731 Not tainted 6.1.28-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 Call trace: dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056 check_noncircular+0x2cc/0x378 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056 lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x70/0x2bc kernel/cpu.c:310 static_key_slow_inc+0x1c/0x38 kernel/jump_label.c:158 freezer_css_online+0xbc/0x150 kernel/cgroup/legacy_freezer.c:117 online_css+0xc8/0x2b4 kernel/cgroup/cgroup.c:5476 css_create kernel/cgroup/cgroup.c:5547 [inline] cgroup_apply_control_enable+0x6d8/0x9ac kernel/cgroup/cgroup.c:3235 cgroup_mkdir+0x9b4/0xd50 kernel/cgroup/cgroup.c:5743 kernfs_iop_mkdir+0x114/0x160 fs/kernfs/dir.c:1196 vfs_mkdir+0x334/0x4e4 fs/namei.c:4036 do_mkdirat+0x20c/0x610 fs/namei.c:4061 __do_sys_mkdirat fs/namei.c:4076 [inline] __se_sys_mkdirat fs/namei.c:4074 [inline] __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4074 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581