====================================================== WARNING: possible circular locking dependency detected 6.4.0-rc5-syzkaller-00002-gf8dba31b0a82 #0 Not tainted ------------------------------------------------------ syz-executor.4/10624 is trying to acquire lock: ffffffff8cdc3ff0 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_inc+0x12/0x30 kernel/jump_label.c:185 but task is already holding lock: ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4f/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}: lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5705 __mutex_lock_common+0x1d8/0x2530 kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x1b/0x20 kernel/locking/mutex.c:799 freezer_change_state kernel/cgroup/legacy_freezer.c:389 [inline] freezer_write+0xa8/0x3f0 kernel/cgroup/legacy_freezer.c:429 cgroup_file_write+0x2ca/0x6a0 kernel/cgroup/cgroup.c:4071 kernfs_fop_write_iter+0x3a6/0x4f0 fs/kernfs/file.c:334 call_write_iter include/linux/fs.h:1868 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x790/0xb20 fs/read_write.c:584 ksys_write+0x1a0/0x2c0 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 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:3113 [inline] check_prevs_add kernel/locking/lockdep.c:3232 [inline] validate_chain+0x166b/0x58f0 kernel/locking/lockdep.c:3847 __lock_acquire+0x1316/0x2070 kernel/locking/lockdep.c:5088 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5705 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x42/0x150 kernel/cpu.c:310 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:185 freezer_css_online+0xc6/0x150 kernel/cgroup/legacy_freezer.c:117 online_css+0xba/0x260 kernel/cgroup/cgroup.c:5491 css_create kernel/cgroup/cgroup.c:5562 [inline] cgroup_apply_control_enable+0x7d1/0xae0 kernel/cgroup/cgroup.c:3249 cgroup_mkdir+0xd8f/0x1000 kernel/cgroup/cgroup.c:5758 kernfs_iop_mkdir+0x279/0x400 fs/kernfs/dir.c:1219 vfs_mkdir+0x29d/0x450 fs/namei.c:4115 do_mkdirat+0x264/0x520 fs/namei.c:4138 __do_sys_mkdirat fs/namei.c:4153 [inline] __se_sys_mkdirat fs/namei.c:4151 [inline] __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 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); rlock(cpu_hotplug_lock); *** DEADLOCK *** 4 locks held by syz-executor.4/10624: #0: ffff8880787de460 (sb_writers#11){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:394 #1: ffff88803214b900 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:810 [inline] #1: ffff88803214b900 (&type->i_mutex_dir_key#7/1){+.+.}-{3:3}, at: filename_create+0x260/0x530 fs/namei.c:3884 #2: ffffffff8cf4f768 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_lock include/linux/cgroup.h:370 [inline] #2: ffffffff8cf4f768 (cgroup_mutex){+.+.}-{3:3}, at: cgroup_kn_lock_live+0xe9/0x290 kernel/cgroup/cgroup.c:1683 #3: ffffffff8cf5a688 (freezer_mutex){+.+.}-{3:3}, at: freezer_css_online+0x4f/0x150 kernel/cgroup/legacy_freezer.c:111 stack backtrace: CPU: 0 PID: 10624 Comm: syz-executor.4 Not tainted 6.4.0-rc5-syzkaller-00002-gf8dba31b0a82 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 check_noncircular+0x2fe/0x3b0 kernel/locking/lockdep.c:2188 check_prev_add kernel/locking/lockdep.c:3113 [inline] check_prevs_add kernel/locking/lockdep.c:3232 [inline] validate_chain+0x166b/0x58f0 kernel/locking/lockdep.c:3847 __lock_acquire+0x1316/0x2070 kernel/locking/lockdep.c:5088 lock_acquire+0x1e3/0x520 kernel/locking/lockdep.c:5705 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x42/0x150 kernel/cpu.c:310 static_key_slow_inc+0x12/0x30 kernel/jump_label.c:185 freezer_css_online+0xc6/0x150 kernel/cgroup/legacy_freezer.c:117 online_css+0xba/0x260 kernel/cgroup/cgroup.c:5491 css_create kernel/cgroup/cgroup.c:5562 [inline] cgroup_apply_control_enable+0x7d1/0xae0 kernel/cgroup/cgroup.c:3249 cgroup_mkdir+0xd8f/0x1000 kernel/cgroup/cgroup.c:5758 kernfs_iop_mkdir+0x279/0x400 fs/kernfs/dir.c:1219 vfs_mkdir+0x29d/0x450 fs/namei.c:4115 do_mkdirat+0x264/0x520 fs/namei.c:4138 __do_sys_mkdirat fs/namei.c:4153 [inline] __se_sys_mkdirat fs/namei.c:4151 [inline] __x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4151 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fcbc528c169 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:00007fcbc5fa1168 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007fcbc53ac050 RCX: 00007fcbc528c169 RDX: 00000000000001ff RSI: 0000000020000180 RDI: 0000000000000006 RBP: 00007fcbc52e7ca1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fff140a47af R14: 00007fcbc5fa1300 R15: 0000000000022000