======================================================
WARNING: possible circular locking dependency detected
6.1.0-rc2-syzkaller #0 Not tainted
------------------------------------------------------
syz-executor.0/3974 is trying to acquire lock:
ffffffff8b633c30 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0xd/0x20 kernel/jump_label.c:158

but task is already holding lock:
ffffffff8b7d73e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline]
ffffffff8b7d73e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0x74/0x6d0 kernel/cgroup/legacy_freezer.c:426

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (freezer_mutex){+.+.}-{3:3}:
       __mutex_lock_common kernel/locking/mutex.c:603 [inline]
       __mutex_lock+0x12f/0x1360 kernel/locking/mutex.c:747
       freezer_attach+0x70/0x1a0 kernel/cgroup/legacy_freezer.c:163
       cgroup_migrate_execute+0x9e0/0xfe0 kernel/cgroup/cgroup.c:2615
       cgroup_attach_task+0x30e/0x620 kernel/cgroup/cgroup.c:2906
       __cgroup1_procs_write.constprop.0+0x2f2/0x400 kernel/cgroup/cgroup-v1.c:523
       cgroup_file_write+0x195/0x640 kernel/cgroup/cgroup.c:4057
       kernfs_fop_write_iter+0x355/0x530 fs/kernfs/file.c:330
       call_write_iter include/linux/fs.h:2191 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x823/0xd50 fs/read_write.c:584
       ksys_write+0xf2/0x1c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #1 (cgroup_threadgroup_rwsem){++++}-{0:0}:
       percpu_down_write+0x53/0x390 kernel/locking/percpu-rwsem.c:227
       cgroup_attach_lock kernel/cgroup/cgroup.c:2431 [inline]
       cgroup_procs_write_start+0x112/0x490 kernel/cgroup/cgroup.c:2935
       __cgroup_procs_write+0xcc/0x540 kernel/cgroup/cgroup.c:5135
       cgroup_procs_write+0x12/0x20 kernel/cgroup/cgroup.c:5171
       cgroup_file_write+0x195/0x640 kernel/cgroup/cgroup.c:4057
       kernfs_fop_write_iter+0x355/0x530 fs/kernfs/file.c:330
       call_write_iter include/linux/fs.h:2191 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x823/0xd50 fs/read_write.c:584
       ksys_write+0xf2/0x1c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 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:3097 [inline]
       check_prevs_add kernel/locking/lockdep.c:3216 [inline]
       validate_chain kernel/locking/lockdep.c:3831 [inline]
       __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
       lock_acquire kernel/locking/lockdep.c:5668 [inline]
       lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       cpus_read_lock+0x3b/0xd0 kernel/cpu.c:310
       static_key_slow_inc+0xd/0x20 kernel/jump_label.c:158
       freezer_apply_state+0x121/0x190 kernel/cgroup/legacy_freezer.c:353
       freezer_change_state kernel/cgroup/legacy_freezer.c:398 [inline]
       freezer_write+0x39d/0x6d0 kernel/cgroup/legacy_freezer.c:426
       cgroup_file_write+0x195/0x640 kernel/cgroup/cgroup.c:4057
       kernfs_fop_write_iter+0x355/0x530 fs/kernfs/file.c:330
       call_write_iter include/linux/fs.h:2191 [inline]
       new_sync_write fs/read_write.c:491 [inline]
       vfs_write+0x823/0xd50 fs/read_write.c:584
       ksys_write+0xf2/0x1c0 fs/read_write.c:637
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Chain exists of:
  cpu_hotplug_lock --> cgroup_threadgroup_rwsem --> freezer_mutex

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(freezer_mutex);
                               lock(cgroup_threadgroup_rwsem);
                               lock(freezer_mutex);
  lock(cpu_hotplug_lock);

 *** DEADLOCK ***

5 locks held by syz-executor.0/3974:
 #0: ffff88807e5fd268 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x9a/0xb0 fs/file.c:1037
 #1: ffff88807c01a460 (sb_writers#11){.+.+}-{0:0}, at: ksys_write+0xf2/0x1c0 fs/read_write.c:637
 #2: ffff888073627088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x218/0x530 fs/kernfs/file.c:321
 #3: ffff888016f720f0 (kn->active#62){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x23c/0x530 fs/kernfs/file.c:322
 #4: ffffffff8b7d73e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline]
 #4: ffffffff8b7d73e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0x74/0x6d0 kernel/cgroup/legacy_freezer.c:426

stack backtrace:
CPU: 1 PID: 3974 Comm: syz-executor.0 Not tainted 6.1.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x5b/0x81 lib/dump_stack.c:106
 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
 check_prev_add kernel/locking/lockdep.c:3097 [inline]
 check_prevs_add kernel/locking/lockdep.c:3216 [inline]
 validate_chain kernel/locking/lockdep.c:3831 [inline]
 __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
 lock_acquire kernel/locking/lockdep.c:5668 [inline]
 lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
 percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
 cpus_read_lock+0x3b/0xd0 kernel/cpu.c:310
 static_key_slow_inc+0xd/0x20 kernel/jump_label.c:158
 freezer_apply_state+0x121/0x190 kernel/cgroup/legacy_freezer.c:353
 freezer_change_state kernel/cgroup/legacy_freezer.c:398 [inline]
 freezer_write+0x39d/0x6d0 kernel/cgroup/legacy_freezer.c:426
 cgroup_file_write+0x195/0x640 kernel/cgroup/cgroup.c:4057
 kernfs_fop_write_iter+0x355/0x530 fs/kernfs/file.c:330
 call_write_iter include/linux/fs.h:2191 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x823/0xd50 fs/read_write.c:584
 ksys_write+0xf2/0x1c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f54bf28c169
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f54bedff168 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f54bf3abf80 RCX: 00007f54bf28c169
RDX: 0000000000000007 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00007f54bf2e7ca1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff15b0e33f R14: 00007f54bedff300 R15: 0000000000022000
 </TASK>