Warning: Permanently added '10.128.1.140' (ED25519) to the list of known hosts. [*] Starting reproducer for circular locking in cgroup_kn_lock_live... [+] Detected cgroup mount options: blkio,devices,freezer,net_prio [+] mkdir /tmp/cg successful. [+] mount cgroup v1 successful. [+] mkdir /tmp/cg/sub successful (cgroup_mutex -> rtnl_mutex established). [+] open /sys/module/block2mtd/parameters/block2mtd successful. [+] write path '/tmp/cg/nonexistent_mtd_bdev ' to block2mtd successful. [+] write path '/dev/nonexistent_mtd_bdev ' to block2mtd successful (param_lock -> i_mutex_dir_key established). [+] close block2mtd param_fd successful. [ 143.558514][ T5993] block2mtd: error: cannot open device /tmp/cg/nonexistent_mtd_bdev [ 143.559212][ T5993] block2mtd: error: cannot open device /dev/nonexistent_mtd_bdev [ 143.560808][ T5993] [ 143.579238][ T5993] ====================================================== [ 143.586545][ T5993] WARNING: possible circular locking dependency detected [ 143.593700][ T5993] syzkaller #0 Not tainted [ 143.598213][ T5993] ------------------------------------------------------ [ 143.605550][ T5993] syz-executor140/5993 is trying to acquire lock: [ 143.612094][ T5993] ffffffff8fe523e0 (cgroup_mutex){+.+.}-{4:4}, at: cgroup_kn_lock_live+0x116/0x520 [ 143.621598][ T5993] [ 143.621598][ T5993] but task is already holding lock: [ 143.629060][ T5993] ffff888071de6740 (&type->i_mutex_dir_key#7){++++}-{4:4}, at: vfs_rmdir+0xed/0x8a0 [ 143.639056][ T5993] [ 143.639056][ T5993] which lock already depends on the new lock. [ 143.639056][ T5993] [ 143.649563][ T5993] [ 143.649563][ T5993] the existing dependency chain (in reverse order) is: [ 143.658962][ T5993] [ 143.658962][ T5993] -> #3 (&type->i_mutex_dir_key#7){++++}-{4:4}: [ 143.667528][ T5993] lock_acquire+0x1d1/0x380 [ 143.672699][ T5993] down_read+0x99/0x4c0 [ 143.677455][ T5993] lookup_slow+0x42/0x70 [ 143.682356][ T5993] path_lookupat+0x5e8/0xc40 [ 143.687497][ T5993] filename_lookup+0x202/0x590 [ 143.692831][ T5993] kern_path+0x37/0x50 [ 143.697816][ T5993] lookup_bdev+0xd8/0x2a0 [ 143.702906][ T5993] bdev_file_open_by_path+0x82/0x330 [ 143.709058][ T5993] block2mtd_setup2.isra.0+0x2f8/0xc60 [ 143.715274][ T5993] block2mtd_setup+0xbd/0xd0 [ 143.720720][ T5993] param_attr_store+0x199/0x300 [ 143.726240][ T5993] module_attr_store+0x58/0x80 [ 143.731772][ T5993] sysfs_kf_write+0xf2/0x150 [ 143.737179][ T5993] kernfs_fop_write_iter+0x3e0/0x5f0 [ 143.743115][ T5993] vfs_write+0x6af/0x1050 [ 143.748345][ T5993] ksys_write+0x12a/0x250 [ 143.753528][ T5993] do_syscall_64+0x121/0x770 [ 143.758690][ T5993] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 143.765415][ T5993] [ 143.765415][ T5993] -> #2 (param_lock){+.+.}-{4:4}: [ 143.773058][ T5993] lock_acquire+0x1d1/0x380 [ 143.778354][ T5993] __mutex_lock+0x1a4/0x1bd0 [ 143.783651][ T5993] ieee80211_init_rate_ctrl_alg+0x1df/0x3b0 [ 143.790127][ T5993] ieee80211_register_hw+0x2c5b/0x45c0 [ 143.796172][ T5993] mac80211_hwsim_new_radio+0x2b08/0x6510 [ 143.802477][ T5993] init_mac80211_hwsim+0x5e2/0x6f0 [ 143.808535][ T5993] do_one_initcall+0x11c/0x6f0 [ 143.813936][ T5993] kernel_init_freeable+0x6ea/0x7b0 [ 143.820030][ T5993] kernel_init+0x21/0x1e0 [ 143.824909][ T5993] ret_from_fork+0x730/0xd60 [ 143.830065][ T5993] ret_from_fork_asm+0x1a/0x30 [ 143.835483][ T5993] [ 143.835483][ T5993] -> #1 (rtnl_mutex){+.+.}-{4:4}: [ 143.842840][ T5993] lock_acquire+0x1d1/0x380 [ 143.847922][ T5993] __mutex_lock+0x1a4/0x1bd0 [ 143.853228][ T5993] cgrp_css_online+0xa1/0x1f0 [ 143.858637][ T5993] online_css+0xb2/0x350 [ 143.863441][ T5993] cgroup_apply_control_enable+0xa8d/0xdd0 [ 143.869889][ T5993] cgroup_mkdir+0x57f/0x1330 [ 143.875069][ T5993] kernfs_iop_mkdir+0x111/0x190 [ 143.880766][ T5993] vfs_mkdir+0x364/0x850 [ 143.885573][ T5993] filename_mkdirat+0x48b/0x5e0 [ 143.891094][ T5993] __x64_sys_mkdirat+0x89/0xc0 [ 143.896800][ T5993] do_syscall_64+0x121/0x770 [ 143.902446][ T5993] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 143.909431][ T5993] [ 143.909431][ T5993] -> #0 (cgroup_mutex){+.+.}-{4:4}: [ 143.917087][ T5993] check_prev_add+0xeb/0xe60 [ 143.923033][ T5993] __lock_acquire+0x1528/0x1f40 [ 143.928725][ T5993] lock_acquire+0x1d1/0x380 [ 143.934080][ T5993] __mutex_lock+0x1a4/0x1bd0 [ 143.939455][ T5993] cgroup_kn_lock_live+0x116/0x520 [ 143.945574][ T5993] cgroup_rmdir+0x22/0x2f0 [ 143.950708][ T5993] kernfs_iop_rmdir+0x106/0x170 [ 143.956282][ T5993] vfs_rmdir+0x328/0x8a0 [ 143.961192][ T5993] filename_rmdir+0x31a/0x5c0 [ 143.966442][ T5993] __x64_sys_rmdir+0x46/0x70 [ 143.971615][ T5993] do_syscall_64+0x121/0x770 [ 143.977027][ T5993] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 143.983744][ T5993] [ 143.983744][ T5993] other info that might help us debug this: [ 143.983744][ T5993] [ 143.994916][ T5993] Chain exists of: [ 143.994916][ T5993] cgroup_mutex --> param_lock --> &type->i_mutex_dir_key#7 [ 143.994916][ T5993] [ 144.008225][ T5993] Possible unsafe locking scenario: [ 144.008225][ T5993] [ 144.016105][ T5993] CPU0 CPU1 [ 144.022870][ T5993] ---- ---- [ 144.029264][ T5993] lock(&type->i_mutex_dir_key#7); [ 144.035024][ T5993] lock(param_lock); [ 144.041723][ T5993] lock(&type->i_mutex_dir_key#7); [ 144.049775][ T5993] lock(cgroup_mutex); [ 144.054056][ T5993] [ 144.054056][ T5993] *** DEADLOCK *** [ 144.054056][ T5993] [ 144.062482][ T5993] locks held by syz-executor140/5993: 3, last CPU#0: [ 144.069533][ T5993] #0: ffff88807ea22460 (sb_writers#10){.+.+}-{0:0}, at: filename_rmdir+0x1ff/0x5c0 [ 144.079243][ T5993] #1: ffff888076d68f80 (&type->i_mutex_dir_key#7/1){+.+.}-{4:4}, at: filename_rmdir+0x258/0x5c0 [ 144.090216][ T5993] #2: ffff888071de6740 (&type->i_mutex_dir_key#7){++++}-{4:4}, at: vfs_rmdir+0xed/0x8a0 [ 144.100492][ T5993] [ 144.100492][ T5993] stack backtrace: [ 144.107229][ T5993] CPU: 0 UID: 0 PID: 5993 Comm: syz-executor140 Not tainted syzkaller #0 PREEMPT(full) [ 144.117076][ T5993] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026 [ 144.127553][ T5993] Call Trace: [ 144.130875][ T5993] [ 144.133827][ T5993] dump_stack_lvl+0x100/0x190 [ 144.138569][ T5993] print_circular_bug.cold+0x178/0x1be [ 144.144370][ T5993] check_noncircular+0x146/0x160 [ 144.149384][ T5993] check_prev_add+0xeb/0xe60 [ 144.154307][ T5993] __lock_acquire+0x1528/0x1f40 [ 144.159245][ T5993] lock_acquire+0x1d1/0x380 [ 144.163887][ T5993] ? cgroup_kn_lock_live+0x116/0x520 [ 144.169556][ T5993] ? __pfx___might_resched+0x10/0x10 [ 144.174995][ T5993] __mutex_lock+0x1a4/0x1bd0 [ 144.179900][ T5993] ? cgroup_kn_lock_live+0x116/0x520 [ 144.185770][ T5993] ? cgroup_kn_lock_live+0x116/0x520 [ 144.192079][ T5993] ? __lock_acquire+0x5c0/0x1f40 [ 144.197187][ T5993] ? __pfx___mutex_lock+0x10/0x10 [ 144.202613][ T5993] ? __lock_acquire+0x5c0/0x1f40 [ 144.208078][ T5993] ? find_held_lock+0x2b/0x80 [ 144.213327][ T5993] ? cgroup_kn_lock_live+0x290/0x520 [ 144.219200][ T5993] ? cgroup_kn_lock_live+0x290/0x520 [ 144.225472][ T5993] ? cgroup_kn_lock_live+0x116/0x520 [ 144.231146][ T5993] cgroup_kn_lock_live+0x116/0x520 [ 144.236882][ T5993] ? kernfs_root+0xee/0x2a0 [ 144.241937][ T5993] cgroup_rmdir+0x22/0x2f0 [ 144.246793][ T5993] kernfs_iop_rmdir+0x106/0x170 [ 144.251892][ T5993] ? security_inode_rmdir+0xe2/0x280 [ 144.257392][ T5993] vfs_rmdir+0x328/0x8a0 [ 144.261956][ T5993] filename_rmdir+0x31a/0x5c0 [ 144.266712][ T5993] ? __pfx_filename_rmdir+0x10/0x10 [ 144.271980][ T5993] ? do_getname+0x191/0x390 [ 144.276546][ T5993] __x64_sys_rmdir+0x46/0x70 [ 144.281530][ T5993] do_syscall_64+0x121/0x770 [ 144.286518][ T5993] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 144.292767][ T5993] RIP: 0033:0x7f81c4d28557 [ 144.297717][ T5993] Code: 00 00 90 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 00 31 c9 e8 4a 02 02 00 48 83 c4 18 c3 0f 1f 44 00 00 b8 54 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 d8 ff ff ff f7 d8 64 89 02 b8 [ 144.317828][ T5993] RSP: 002b:00007ffe71e77668 EFLAGS: 00000206 ORIG_RAX: 0000000000000054 [ 144.326567][ T5993] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f81c4d28557 [ 144.335495][ T5993] RDX: 0000000000000000 RSI: 00007f81c4db03a3 RDI: 00007f81c4d83e7b [ 144.344464][ T5993] RBP: 00007ffe71e77670 R08: 0000000000000000 R09: 0000000000000000 [ 144.352915][ T5993] R10: 0000000000000000 R11: 0000000000000206 R12: 00007f81c4d83e50 [+] rmdir /tmp/cg/sub successful (lockdep cycle triggered!). [ 144.361888][ T5993] R13: 00007f81c4d83e7b R14: 000000000000001e R15: 0000000000000002 [ 144.370251][ T5993] [+] umount2 /tmp/cg successful. [+] rmdir /tmp/cg successful. [+] Reproducer finished successfully.