====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.0.621/8877 is trying to acquire lock: ffff88805c645928 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1044 [inline] ffff88805c645928 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: lookup_slow+0x42/0x70 fs/namei.c:1931 but task is already holding lock: ffffffff8e69bd80 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:602 [inline] ffffffff8e69bd80 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xec/0x300 kernel/params.c:587 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (param_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820 ieee80211_rate_control_ops_get net/mac80211/rate.c:223 [inline] rate_control_alloc net/mac80211/rate.c:269 [inline] ieee80211_init_rate_ctrl_alg+0x1df/0x3b0 net/mac80211/rate.c:1016 ieee80211_register_hw+0x2c20/0x4570 net/mac80211/main.c:1559 mac80211_hwsim_new_radio+0x2a01/0x5aa0 drivers/net/wireless/virtual/mac80211_hwsim.c:6019 init_mac80211_hwsim+0x3f2/0x830 drivers/net/wireless/virtual/mac80211_hwsim.c:7394 do_one_initcall+0x121/0x750 init/main.c:1392 do_initcall_level init/main.c:1454 [inline] do_initcalls init/main.c:1470 [inline] do_basic_setup init/main.c:1490 [inline] kernel_init_freeable+0x6ea/0x7b0 init/main.c:1703 kernel_init+0x1f/0x1e0 init/main.c:1593 ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #2 (rtnl_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820 cgrp_css_online+0xa1/0x1f0 net/core/netprio_cgroup.c:157 online_css+0xb2/0x350 kernel/cgroup/cgroup.c:5720 css_create kernel/cgroup/cgroup.c:5798 [inline] cgroup_apply_control_enable+0xa8d/0xdd0 kernel/cgroup/cgroup.c:3351 cgroup_mkdir+0x59c/0x1310 kernel/cgroup/cgroup.c:5999 kernfs_iop_mkdir+0x111/0x190 fs/kernfs/dir.c:1306 vfs_mkdir+0x361/0x850 fs/namei.c:5261 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5294 __do_sys_mkdirat fs/namei.c:5315 [inline] __se_sys_mkdirat fs/namei.c:5312 [inline] __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5312 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (cgroup_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:646 [inline] __mutex_lock+0x1a4/0x1b10 kernel/locking/mutex.c:820 cgroup_lock include/linux/cgroup.h:456 [inline] cgroup_kn_lock_live+0x116/0x520 kernel/cgroup/cgroup.c:1683 cgroup_rmdir+0x26/0x2e0 kernel/cgroup/cgroup.c:6259 kernfs_iop_rmdir+0x106/0x170 fs/kernfs/dir.c:1324 vfs_rmdir fs/namei.c:5366 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5339 filename_rmdir+0x31a/0x5c0 fs/namei.c:5421 __do_sys_rmdir fs/namei.c:5444 [inline] __se_sys_rmdir fs/namei.c:5441 [inline] __x64_sys_rmdir+0x46/0x70 fs/namei.c:5441 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&type->i_mutex_dir_key#6){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 down_read+0x99/0x450 kernel/locking/rwsem.c:1568 inode_lock_shared include/linux/fs.h:1044 [inline] lookup_slow+0x42/0x70 fs/namei.c:1931 walk_component fs/namei.c:2278 [inline] lookup_last fs/namei.c:2785 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2809 filename_lookup+0x202/0x590 fs/namei.c:2838 kern_path+0x37/0x50 fs/namei.c:3044 lookup_bdev+0xd8/0x280 block/bdev.c:1213 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1086 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2.isra.0+0x2ee/0xc70 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0xbd/0xd0 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x199/0x300 kernel/params.c:589 module_attr_store+0x58/0x80 kernel/params.c:904 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#6 --> rtnl_mutex --> param_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(param_lock); lock(rtnl_mutex); lock(param_lock); rlock(&type->i_mutex_dir_key#6); *** DEADLOCK *** 5 locks held by syz.0.621/8877: #0: ffff88807ee52b70 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2aa/0x380 fs/file.c:1261 #1: ffff88803736c410 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:740 #2: ffff88807a14c880 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343 #3: ffff8880350ad5a8 (kn->active#4){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #3: ffff8880350ad5a8 (kn->active#4){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:344 #4: ffffffff8e69bd80 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:602 [inline] #4: ffffffff8e69bd80 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xec/0x300 kernel/params.c:587 stack backtrace: CPU: 0 UID: 0 PID: 8877 Comm: syz.0.621 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_circular_bug.cold+0x178/0x1c7 kernel/locking/lockdep.c:2043 check_noncircular+0x146/0x160 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x14b8/0x2630 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x1b1/0x370 kernel/locking/lockdep.c:5825 down_read+0x99/0x450 kernel/locking/rwsem.c:1568 inode_lock_shared include/linux/fs.h:1044 [inline] lookup_slow+0x42/0x70 fs/namei.c:1931 walk_component fs/namei.c:2278 [inline] lookup_last fs/namei.c:2785 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2809 filename_lookup+0x202/0x590 fs/namei.c:2838 kern_path+0x37/0x50 fs/namei.c:3044 lookup_bdev+0xd8/0x280 block/bdev.c:1213 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1086 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2.isra.0+0x2ee/0xc70 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0xbd/0xd0 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x199/0x300 kernel/params.c:589 module_attr_store+0x58/0x80 kernel/params.c:904 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x10b/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f203d59ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f203e484028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f203d816270 RCX: 00007f203d59ce59 RDX: 0000000000000272 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 00007f203d632d6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f203d816308 R14: 00007f203d816270 R15: 00007ffcb3b264e8 block2mtd: error: cannot open device