====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.16/4505 is trying to acquire lock: ffff0000d5a96460 (sb_writers#10){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:402 but task is already holding lock: ffff0000d1280d40 (&wdev->mtx){+.+.}-{3:3}, at: wdev_lock net/wireless/core.h:231 [inline] ffff0000d1280d40 (&wdev->mtx){+.+.}-{3:3}, at: cfg80211_wext_siwgenie+0xc8/0x370 net/wireless/wext-sme.c:340 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&wdev->mtx){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 wdev_lock net/wireless/core.h:231 [inline] cfg80211_wext_siwgenie+0xc8/0x370 net/wireless/wext-sme.c:340 __cfg80211_wext_siwgenie+0x3c/0x50 net/wireless/wext-compat.c:1620 ioctl_standard_iw_point+0x7b4/0xcf8 net/wireless/wext-core.c:848 ioctl_standard_call+0xb8/0x24c net/wireless/wext-core.c:1033 wireless_process_ioctl net/wireless/wext-core.c:-1 [inline] wext_ioctl_dispatch+0x168/0x3d0 net/wireless/wext-core.c:997 wext_handle_ioctl+0x1ac/0x370 net/wireless/wext-core.c:1058 sock_ioctl+0x138/0x828 net/socket.c:1253 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:585 -> #3 (rtnl_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 rtnl_lock+0x20/0x2c net/core/rtnetlink.c:74 cgrp_css_online+0x8c/0x2cc net/core/netprio_cgroup.c:157 online_css+0xc8/0x2b0 kernel/cgroup/cgroup.c:5520 css_create kernel/cgroup/cgroup.c:5591 [inline] cgroup_apply_control_enable+0x704/0x9e0 kernel/cgroup/cgroup.c:3283 cgroup_mkdir+0x964/0xcf8 kernel/cgroup/cgroup.c:5789 kernfs_iop_mkdir+0x118/0x164 fs/kernfs/dir.c:1221 vfs_mkdir+0x314/0x4d8 fs/namei.c:4157 do_mkdirat+0x1b8/0x3ec fs/namei.c:4182 __do_sys_mkdirat fs/namei.c:4197 [inline] __se_sys_mkdirat fs/namei.c:4195 [inline] __arm64_sys_mkdirat+0x90/0xa8 fs/namei.c:4195 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:585 -> #2 (cgroup_mutex){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 cgroup_lock include/linux/cgroup.h:442 [inline] cgroup_lock_and_drain_offline+0x94/0x4a4 kernel/cgroup/cgroup.c:3158 cgroup_kn_lock_live+0xd4/0x258 kernel/cgroup/cgroup.c:1698 cgroup_subtree_control_write+0x2a8/0xde4 kernel/cgroup/cgroup.c:3473 cgroup_file_write+0x258/0x584 kernel/cgroup/cgroup.c:4101 kernfs_fop_write_iter+0x390/0x4b4 fs/kernfs/file.c:352 call_write_iter include/linux/fs.h:2271 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x3c8/0x7c8 fs/read_write.c:584 ksys_write+0x12c/0x228 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+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:585 -> #1 (&of->mutex){+.+.}-{3:3}: __mutex_lock_common+0x1a0/0x1f3c kernel/locking/mutex.c:603 __mutex_lock kernel/locking/mutex.c:747 [inline] mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799 kernfs_fop_write_iter+0x1b8/0x4b4 fs/kernfs/file.c:343 call_write_iter include/linux/fs.h:2271 [inline] new_sync_write fs/read_write.c:491 [inline] vfs_write+0x3c8/0x7c8 fs/read_write.c:584 ksys_write+0x12c/0x228 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+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:585 -> #0 (sb_writers#10){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3504/0x7280 kernel/locking/lockdep.c:5171 lock_acquire+0x210/0x63c kernel/locking/lockdep.c:5790 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1897 [inline] sb_start_write+0x74/0x2ac include/linux/fs.h:1972 mnt_want_write+0x44/0x9c fs/namespace.c:402 open_last_lookups fs/namei.c:3590 [inline] path_openat+0x574/0x27a0 fs/namei.c:3831 do_filp_open+0x198/0x38c fs/namei.c:3861 do_sys_openat2+0x134/0x3fc fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:585 other info that might help us debug this: Chain exists of: sb_writers#10 --> rtnl_mutex --> &wdev->mtx Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&wdev->mtx); lock(rtnl_mutex); lock(&wdev->mtx); rlock(sb_writers#10); *** DEADLOCK *** 1 lock held by syz.0.16/4505: #0: ffff0000d1280d40 (&wdev->mtx){+.+.}-{3:3}, at: wdev_lock net/wireless/core.h:231 [inline] #0: ffff0000d1280d40 (&wdev->mtx){+.+.}-{3:3}, at: cfg80211_wext_siwgenie+0xc8/0x370 net/wireless/wext-sme.c:340 stack backtrace: CPU: 0 PID: 4505 Comm: syz.0.16 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/23/2026 Call trace: dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2088 check_noncircular+0x290/0x370 kernel/locking/lockdep.c:2215 check_prev_add kernel/locking/lockdep.c:3162 [inline] check_prevs_add kernel/locking/lockdep.c:3281 [inline] validate_chain kernel/locking/lockdep.c:3897 [inline] __lock_acquire+0x3504/0x7280 kernel/locking/lockdep.c:5171 lock_acquire+0x210/0x63c kernel/locking/lockdep.c:5790 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] __sb_start_write include/linux/fs.h:1897 [inline] sb_start_write+0x74/0x2ac include/linux/fs.h:1972 mnt_want_write+0x44/0x9c fs/namespace.c:402 open_last_lookups fs/namei.c:3590 [inline] path_openat+0x574/0x27a0 fs/namei.c:3831 do_filp_open+0x198/0x38c fs/namei.c:3861 do_sys_openat2+0x134/0x3fc fs/open.c:1320 do_sys_open fs/open.c:1336 [inline] __do_sys_openat fs/open.c:1352 [inline] __se_sys_openat fs/open.c:1347 [inline] __arm64_sys_openat+0x11c/0x150 fs/open.c:1347 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204 el0_svc+0x58/0x12c 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:585