====================================================== WARNING: possible circular locking dependency detected 6.1.34-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor192/3546 is trying to acquire lock: ffffffff8cdc4970 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 but task is already holding lock: ffffffff8cf5a608 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4b/0x140 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}: lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669 __mutex_lock_common+0x1d4/0x2520 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799 freezer_change_state kernel/cgroup/legacy_freezer.c:389 [inline] freezer_write+0xa4/0x3f0 kernel/cgroup/legacy_freezer.c:429 cgroup_file_write+0x2c6/0x690 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3a2/0x4f0 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+0x7ae/0xba0 fs/read_write.c:584 ksys_write+0x19c/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #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+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x3e/0x150 kernel/cpu.c:310 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 freezer_css_online+0xc2/0x140 kernel/cgroup/legacy_freezer.c:117 online_css+0xba/0x260 kernel/cgroup/cgroup.c:5476 css_create kernel/cgroup/cgroup.c:5547 [inline] cgroup_apply_control_enable+0x7d1/0xae0 kernel/cgroup/cgroup.c:3235 cgroup_mkdir+0xd8b/0xff0 kernel/cgroup/cgroup.c:5743 kernfs_iop_mkdir+0x275/0x400 fs/kernfs/dir.c:1196 vfs_mkdir+0x3b6/0x590 fs/namei.c:4036 do_mkdirat+0x260/0x520 fs/namei.c:4061 __do_sys_mkdirat fs/namei.c:4076 [inline] __se_sys_mkdirat fs/namei.c:4074 [inline] __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4074 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd 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-executor192/3546: #0: ffff88802201e460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x3b/0x80 fs/namespace.c:393 #1: ffff88807554d080 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:791 [inline] #1: ffff88807554d080 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: filename_create+0x256/0x530 fs/namei.c:3807 #2: ffffffff8cf4f6a8 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xe5/0x290 kernel/cgroup/cgroup.c:1667 #3: ffffffff8cf5a608 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4b/0x140 kernel/cgroup/legacy_freezer.c:111 stack backtrace: CPU: 0 PID: 3546 Comm: syz-executor192 Not tainted 6.1.34-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 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+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x1f8/0x5a0 kernel/locking/lockdep.c:5669 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x3e/0x150 kernel/cpu.c:310 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 freezer_css_online+0xc2/0x140 kernel/cgroup/legacy_freezer.c:117 online_css+0xba/0x260 kernel/cgroup/cgroup.c:5476 css_create kernel/cgroup/cgroup.c:5547 [inline] cgroup_apply_control_enable+0x7d1/0xae0 kernel/cgroup/cgroup.c:3235 cgroup_mkdir+0xd8b/0xff0 kernel/cgroup/cgroup.c:5743 kernfs_iop_mkdir+0x275/0x400 fs/kernfs/dir.c:1196 vfs_mkdir+0x3b6/0x590 fs/namei.c:4036 do_mkdirat+0x260/0x520 fs/namei.c:4061 __do_sys_mkdirat fs/namei.c:4076 [inline] __se_sys_mkdirat fs/namei.c:4074 [inline] __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4074 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f9455067dc9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffbc378068 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f9455067dc9 RDX: 00000000000001ff RSI: 0000000020000180 RDI: 0000000000000003 RBP: 0000000000000000 R08: 00007fffbc378090 R09: 00007fffbc378090 R10: 00007fffbc378090 R11: 0000000000000246 R12: 00007fffbc37808c R13: 00007fffbc3780a0 R14: 00007fffbc3780e0 R15: 0000000000000000