====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc6-syzkaller-00015-gc3eb11fbb826 #0 Not tainted ------------------------------------------------------ syz-executor392/3641 is trying to acquire lock: ffffffff8cfc4470 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 but task is already holding lock: ffffffff8d15a7e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline] ffffffff8d15a7e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0x9f/0x3b0 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}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 __mutex_lock_common+0x1bd/0x26e0 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799 freezer_attach+0x82/0x290 kernel/cgroup/legacy_freezer.c:163 cgroup_migrate_execute+0x7e9/0x1020 kernel/cgroup/cgroup.c:2615 cgroup_attach_task+0x54d/0x6a0 kernel/cgroup/cgroup.c:2906 __cgroup1_procs_write+0x2a9/0x400 kernel/cgroup/cgroup-v1.c:523 cgroup_file_write+0x2ab/0x730 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3ac/0x500 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+0x7dc/0xc50 fs/read_write.c:584 ksys_write+0x177/0x2a0 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 -> #1 (cgroup_threadgroup_rwsem){++++}-{0:0}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 percpu_down_write+0x50/0x300 kernel/locking/percpu-rwsem.c:227 cgroup_attach_lock kernel/cgroup/cgroup.c:2431 [inline] cgroup_procs_write_start+0x1c8/0x640 kernel/cgroup/cgroup.c:2935 __cgroup_procs_write+0xe3/0x490 kernel/cgroup/cgroup.c:5135 cgroup_procs_write+0x23/0x40 kernel/cgroup/cgroup.c:5171 cgroup_file_write+0x2ab/0x730 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3ac/0x500 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+0x7dc/0xc50 fs/read_write.c:584 ksys_write+0x177/0x2a0 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:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055 lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x3e/0x130 kernel/cpu.c:310 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 freezer_apply_state+0x1bb/0x400 kernel/cgroup/legacy_freezer.c:353 freezer_write+0x24a/0x3b0 kernel/cgroup/legacy_freezer.c:426 cgroup_file_write+0x2ab/0x730 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3ac/0x500 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+0x7dc/0xc50 fs/read_write.c:584 ksys_write+0x177/0x2a0 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 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 *** 4 locks held by syz-executor392/3641: #0: ffff8880278ce460 (sb_writers#10){.+.+}-{0:0}, at: vfs_write+0x287/0xc50 fs/read_write.c:580 #1: ffff88801ebc9488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1f3/0x500 fs/kernfs/file.c:321 #2: ffff88814567f2c0 (kn->active#56){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x217/0x500 fs/kernfs/file.c:322 #3: ffffffff8d15a7e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline] #3: ffffffff8d15a7e8 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0x9f/0x3b0 kernel/cgroup/legacy_freezer.c:426 stack backtrace: CPU: 1 PID: 3641 Comm: syz-executor392 Not tainted 6.1.0-rc6-syzkaller-00015-gc3eb11fbb826 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 check_noncircular+0x2cc/0x390 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+0x1898/0x6ae0 kernel/locking/lockdep.c:3831 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055 lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x3e/0x130 kernel/cpu.c:310 static_key_slow_inc+0xe/0x20 kernel/jump_label.c:158 freezer_apply_state+0x1bb/0x400 kernel/cgroup/legacy_freezer.c:353 freezer_write+0x24a/0x3b0 kernel/cgroup/legacy_freezer.c:426 cgroup_file_write+0x2ab/0x730 kernel/cgroup/cgroup.c:4057 kernfs_fop_write_iter+0x3ac/0x500 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+0x7dc/0xc50 fs/read_write.c:584 ksys_write+0x177/0x2a0 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 RIP: 0033:0x7f468b95add9 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:00007fff9d0a5938 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f468b95add9 RDX: 0000000000000007 RSI: 0000000020000040 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00007fff9d0a5960 R09: 00007fff9d0a5960 R10: 00007fff9d0a5960 R11: 0000000000000246 R12: 00007fff9d0a595c R13: 00007fff9d0a5970 R14: 00007fff9d0a59b0 R15: 0000000000000000