====================================================== WARNING: possible circular locking dependency detected 6.1.21-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor440/4316 is trying to acquire lock: ffff8000155f5450 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0x1c/0x38 kernel/jump_label.c:158 but task is already holding lock: ffff800015786748 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline] ffff800015786748 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0xc0/0x434 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+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_attach+0xa8/0x268 kernel/cgroup/legacy_freezer.c:163 cgroup_migrate_execute+0x6f4/0xd34 kernel/cgroup/cgroup.c:2615 cgroup_migrate+0x1c8/0x1e0 kernel/cgroup/cgroup.c:2873 cgroup_attach_task+0x548/0x9e8 kernel/cgroup/cgroup.c:2906 __cgroup1_procs_write+0x2fc/0x404 kernel/cgroup/cgroup-v1.c:523 cgroup1_procs_write+0x38/0x4c kernel/cgroup/cgroup-v1.c:536 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 -> #1 (cgroup_threadgroup_rwsem){++++}-{0:0}: percpu_down_write+0x78/0x320 kernel/locking/percpu-rwsem.c:227 cgroup_attach_lock kernel/cgroup/cgroup.c:2431 [inline] cgroup_procs_write_start+0x1ac/0x5f0 kernel/cgroup/cgroup.c:2935 __cgroup_procs_write+0xec/0x410 kernel/cgroup/cgroup.c:5135 cgroup_procs_write+0x34/0x60 kernel/cgroup/cgroup.c:5171 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_apply_state+0x18c/0x3d0 kernel/cgroup/legacy_freezer.c:353 freezer_write+0x28c/0x434 kernel/cgroup/legacy_freezer.c:426 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 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-executor440/4316: #0: ffff0000d992e460 (sb_writers#9){.+.+}-{0:0}, at: vfs_write+0x244/0x914 fs/read_write.c:580 #1: ffff0000d1d99c88 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1c8/0x48c fs/kernfs/file.c:321 #2: ffff0000c1a89918 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x1e4/0x48c fs/kernfs/file.c:322 #3: ffff800015786748 (freezer_mutex){+.+.}-{3:3}, at: freezer_change_state kernel/cgroup/legacy_freezer.c:387 [inline] #3: ffff800015786748 (freezer_mutex){+.+.}-{3:3}, at: freezer_write+0xc0/0x434 kernel/cgroup/legacy_freezer.c:426 stack backtrace: CPU: 1 PID: 4316 Comm: syz-executor440 Not tainted 6.1.21-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 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_apply_state+0x18c/0x3d0 kernel/cgroup/legacy_freezer.c:353 freezer_write+0x28c/0x434 kernel/cgroup/legacy_freezer.c:426 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