====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G U L ------------------------------------------------------ syz.0.655/8583 is trying to acquire lock: ffff88805f671f18 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1043 [inline] ffff88805f671f18 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: lookup_slow+0x42/0x70 fs/namei.c:1932 but task is already holding lock: ffffffff8e69e048 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:602 [inline] ffffffff8e69e048 (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:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 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+0x2950/0x4140 net/mac80211/main.c:1544 mac80211_hwsim_new_radio+0x2847/0x57d0 drivers/net/wireless/virtual/mac80211_hwsim.c:5809 init_mac80211_hwsim+0x6db/0x7f0 drivers/net/wireless/virtual/mac80211_hwsim.c:7172 do_one_initcall+0x11d/0x760 init/main.c:1382 do_initcall_level init/main.c:1444 [inline] do_initcalls init/main.c:1460 [inline] do_basic_setup init/main.c:1479 [inline] kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692 kernel_init+0x1f/0x1e0 init/main.c:1582 ret_from_fork+0x754/0xd80 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:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 cgrp_css_online+0xa1/0x1f0 net/core/netprio_cgroup.c:157 online_css+0xb2/0x350 kernel/cgroup/cgroup.c:5739 css_create kernel/cgroup/cgroup.c:5827 [inline] cgroup_apply_control_enable+0x8bd/0xbd0 kernel/cgroup/cgroup.c:3390 cgroup_mkdir+0x57f/0x1330 kernel/cgroup/cgroup.c:6028 kernfs_iop_mkdir+0x111/0x190 fs/kernfs/dir.c:1273 vfs_mkdir+0x361/0x850 fs/namei.c:5239 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5272 __do_sys_mkdirat fs/namei.c:5293 [inline] __se_sys_mkdirat fs/namei.c:5290 [inline] __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5290 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 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:614 [inline] __mutex_lock+0x1a2/0x1b90 kernel/locking/mutex.c:776 cgroup_lock include/linux/cgroup.h:394 [inline] cgroup_kn_lock_live+0x116/0x520 kernel/cgroup/cgroup.c:1732 cgroup_rmdir+0x22/0x300 kernel/cgroup/cgroup.c:6305 kernfs_iop_rmdir+0x106/0x170 fs/kernfs/dir.c:1291 vfs_rmdir fs/namei.c:5344 [inline] vfs_rmdir+0x328/0x8a0 fs/namei.c:5317 filename_rmdir+0x31a/0x5c0 fs/namei.c:5399 __do_sys_rmdir fs/namei.c:5422 [inline] __se_sys_rmdir fs/namei.c:5419 [inline] __x64_sys_rmdir+0x46/0x70 fs/namei.c:5419 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 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+0x1cf/0x380 kernel/locking/lockdep.c:5825 down_read+0x99/0x460 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:1043 [inline] lookup_slow+0x42/0x70 fs/namei.c:1932 walk_component fs/namei.c:2279 [inline] lookup_last fs/namei.c:2786 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2810 filename_lookup+0x202/0x590 fs/namei.c:2839 kern_path+0x37/0x50 fs/namei.c:3046 lookup_bdev+0xd8/0x280 block/bdev.c:1221 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1094 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:913 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+0x106/0xf80 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 *** 4 locks held by syz.0.655/8583: #0: ffff888034f2a420 (sb_writers#7){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:740 #1: ffff88805edad888 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x2c2/0x5f0 fs/kernfs/file.c:343 #2: ffff888035ae35a8 (kn->active#4){.+.+}-{0:0}, at: kernfs_get_active_of fs/kernfs/file.c:80 [inline] #2: ffff888035ae35a8 (kn->active#4){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x332/0x5f0 fs/kernfs/file.c:344 #3: ffffffff8e69e048 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:602 [inline] #3: ffffffff8e69e048 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xec/0x300 kernel/params.c:587 stack backtrace: CPU: 0 UID: 0 PID: 8583 Comm: syz.0.655 Tainted: G U L syzkaller #0 PREEMPT(full) Tainted: [U]=USER, [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 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+0x1cf/0x380 kernel/locking/lockdep.c:5825 down_read+0x99/0x460 kernel/locking/rwsem.c:1537 inode_lock_shared include/linux/fs.h:1043 [inline] lookup_slow+0x42/0x70 fs/namei.c:1932 walk_component fs/namei.c:2279 [inline] lookup_last fs/namei.c:2786 [inline] path_lookupat+0x5e8/0xc40 fs/namei.c:2810 filename_lookup+0x202/0x590 fs/namei.c:2839 kern_path+0x37/0x50 fs/namei.c:3046 lookup_bdev+0xd8/0x280 block/bdev.c:1221 bdev_file_open_by_path+0x82/0x330 block/bdev.c:1094 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:913 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+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fe205f9c819 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:00007fe2041ee028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fe206215fa0 RCX: 00007fe205f9c819 RDX: 0000000000000024 RSI: 0000200000000000 RDI: 0000000000000004 RBP: 00007fe206032c91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fe206216038 R14: 00007fe206215fa0 R15: 00007ffc55d557c8 block2mtd: error: cannot open device çinX‘©¼Ëò¨±ÂÚjFBçB>U»;߸³Ilk¬