syzbot


inconsistent lock state in kernfs_path_from_node

Status: upstream: reported on 2026/05/30 05:20
Reported-by: syzbot+99b9352b47a657a7cfcf@syzkaller.appspotmail.com
First crash: 5d22h, last: 5d22h
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 inconsistent lock state in kernfs_path_from_node origin:lts-only 4 C error 15 17h37m 15d 0/3 upstream: reported C repro on 2026/05/20 14:09

Sample crash report:
================================
WARNING: inconsistent lock state
syzkaller #0 Not tainted
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
syz.4.6648/27037 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffffffff8cc84638 (kernfs_rename_lock){....}-{2:2}, at: kernfs_path_from_node+0x85/0xd30 fs/kernfs/dir.c:232
{INITIAL USE} state was registered at:
  lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5662
  __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
  _raw_spin_lock_irq+0xab/0xf0 kernel/locking/spinlock.c:170
  spin_lock_irq include/linux/spinlock.h:376 [inline]
  kernfs_rename_ns+0x550/0x990 fs/kernfs/dir.c:1734
  sysfs_rename_link_ns+0x171/0x1b0 fs/sysfs/symlink.c:192
  device_rename+0x11c/0x1a0 drivers/base/core.c:4562
  dev_change_name+0x376/0x900 net/core/dev.c:1273
  do_setlink+0x93d/0x3e60 net/core/rtnetlink.c:2816
  __rtnl_newlink net/core/rtnetlink.c:3613 [inline]
  rtnl_newlink+0x17d9/0x20a0 net/core/rtnetlink.c:3660
  rtnetlink_rcv_msg+0x87c/0xfc0 net/core/rtnetlink.c:6157
  netlink_rcv_skb+0x1fb/0x450 net/netlink/af_netlink.c:2511
  netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
  netlink_unicast+0x74d/0x8d0 net/netlink/af_netlink.c:1344
  netlink_sendmsg+0x8ad/0xbd0 net/netlink/af_netlink.c:1872
  sock_sendmsg_nosec net/socket.c:718 [inline]
  __sock_sendmsg net/socket.c:730 [inline]
  __sys_sendto+0x497/0x650 net/socket.c:2152
  __do_sys_sendto net/socket.c:2164 [inline]
  __se_sys_sendto net/socket.c:2160 [inline]
  __x64_sys_sendto+0xda/0xf0 net/socket.c:2160
  do_syscall_x64 arch/x86/entry/common.c:46 [inline]
  do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
  entry_SYSCALL_64_after_hwframe+0x68/0xd2
irq event stamp: 850
hardirqs last  enabled at (849): [<ffffffff8a2e9c51>] syscall_enter_from_user_mode+0x21/0x80 kernel/entry/common.c:117
hardirqs last disabled at (850): [<ffffffff8a2e690e>] exc_debug_kernel arch/x86/kernel/traps.c:1039 [inline]
hardirqs last disabled at (850): [<ffffffff8a2e690e>] exc_debug+0x6e/0x130 arch/x86/kernel/traps.c:1175
softirqs last  enabled at (822): [<ffffffff819169b7>] spin_unlock_bh include/linux/spinlock.h:396 [inline]
softirqs last  enabled at (822): [<ffffffff819169b7>] bpf_map_alloc_id+0x87/0xd0 kernel/bpf/syscall.c:386
softirqs last disabled at (820): [<ffffffff81916951>] spin_lock_bh include/linux/spinlock.h:356 [inline]
softirqs last disabled at (820): [<ffffffff81916951>] bpf_map_alloc_id+0x21/0xd0 kernel/bpf/syscall.c:382

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(kernfs_rename_lock);
  <Interrupt>
    lock(kernfs_rename_lock);

 *** DEADLOCK ***

no locks held by syz.4.6648/27037.

stack backtrace:
CPU: 0 PID: 27037 Comm: syz.4.6648 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <#DB>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 lock_acquire+0x2df/0x4a0 kernel/locking/lockdep.c:5653
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
 _raw_spin_lock_irqsave+0xb0/0x100 kernel/locking/spinlock.c:162
 kernfs_path_from_node+0x85/0xd30 fs/kernfs/dir.c:232
 kernfs_path include/linux/kernfs.h:595 [inline]
 cgroup_path include/linux/cgroup.h:674 [inline]
 get_mm_memcg_path+0xb9/0x360 mm/mmap_lock.c:82
 __mmap_lock_do_trace_acquire_returned+0xe7/0x390 mm/mmap_lock.c:102
 __mmap_lock_trace_acquire_returned include/linux/mmap_lock.h:36 [inline]
 mmap_read_trylock include/linux/mmap_lock.h:137 [inline]
 stack_map_get_build_id_offset+0x6b2/0x970 kernel/bpf/stackmap.c:144
 __bpf_get_stackid+0x55d/0x920 kernel/bpf/stackmap.c:250
 bpf_prog_12712c88fd19bd5b+0x21/0x25
 bpf_dispatcher_nop_func include/linux/bpf.h:1012 [inline]
 __bpf_prog_run include/linux/filter.h:596 [inline]
 bpf_prog_run include/linux/filter.h:614 [inline]
 bpf_overflow_handler+0x6e8/0x7c0 kernel/events/core.c:10321
 __perf_event_overflow+0x448/0x610 kernel/events/core.c:9496
 perf_swevent_overflow kernel/events/core.c:9579 [inline]
 perf_swevent_event+0x315/0x570 kernel/events/core.c:9630
 perf_bp_event+0x312/0x3f0 kernel/events/core.c:10518
 hw_breakpoint_handler arch/x86/kernel/hw_breakpoint.c:555 [inline]
 hw_breakpoint_exceptions_notify+0x152/0x470 arch/x86/kernel/hw_breakpoint.c:586
 notifier_call_chain kernel/notifier.c:87 [inline]
 atomic_notifier_call_chain+0x17a/0x2b0 kernel/notifier.c:225
 notify_die+0x141/0x1a0 kernel/notifier.c:593
 notify_debug+0x20/0x30 arch/x86/kernel/traps.c:1018
 exc_debug_kernel arch/x86/kernel/traps.c:1075 [inline]
 exc_debug+0xd9/0x130 arch/x86/kernel/traps.c:1175
 asm_exc_debug+0x1a/0x40 arch/x86/include/asm/idtentry.h:648
RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166
Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90004aafd48 EFLAGS: 00050202
RAX: ffffffff84115b01 RBX: 0000000000000050 RCX: 000000000000004f
RDX: 0000000000000050 RSI: 0000200000000301 RDI: ffffc90004aafdc1
RBP: 0000000000000000 R08: ffffc90004aafe0f R09: 1ffff92000955fc1
R10: dffffc0000000000 R11: fffff52000955fc2 R12: 00007fffffffefb0
R13: 0000000000000050 R14: ffffc90004aafdc0 R15: 0000200000000300
 </#DB>
 <TASK>
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 _copy_from_user+0xf4/0x170 lib/usercopy.c:23
 copy_from_user include/linux/uaccess.h:161 [inline]
 copy_from_bpfptr_offset include/linux/bpfptr.h:53 [inline]
 copy_from_bpfptr include/linux/bpfptr.h:59 [inline]
 __sys_bpf+0x2ea/0x780 kernel/bpf/syscall.c:5004
 __do_sys_bpf kernel/bpf/syscall.c:5135 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5133 [inline]
 __x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:5133
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdca899ce59
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:00007fdca98a7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fdca8c16090 RCX: 00007fdca899ce59
RDX: 0000000000000050 RSI: 0000200000000300 RDI: 0000000000000000
RBP: 00007fdca8a32d6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdca8c16128 R14: 00007fdca8c16090 R15: 00007ffead3d8608
 </TASK>
----------------
Code disassembly (best guess):
   0:	ff c9                	dec    %ecx
   2:	75 f2                	jne    0xfffffff6
   4:	89 d1                	mov    %edx,%ecx
   6:	c1 e9 03             	shr    $0x3,%ecx
   9:	83 e2 07             	and    $0x7,%edx
   c:	f3 48 a5             	rep movsq %ds:(%rsi),%es:(%rdi)
   f:	89 d1                	mov    %edx,%ecx
  11:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi)
  13:	31 c0                	xor    %eax,%eax
  15:	0f 01 ca             	clac
  18:	c3                   	ret
  19:	8d 0c ca             	lea    (%rdx,%rcx,8),%ecx
  1c:	89 ca                	mov    %ecx,%edx
  1e:	eb 20                	jmp    0x40
  20:	0f 01 cb             	stac
  23:	83 fa 40             	cmp    $0x40,%edx
  26:	72 38                	jb     0x60
  28:	89 d1                	mov    %edx,%ecx
* 2a:	f3 a4                	rep movsb %ds:(%rsi),%es:(%rdi) <-- trapping instruction
  2c:	31 c0                	xor    %eax,%eax
  2e:	0f 01 ca             	clac
  31:	c3                   	ret
  32:	89 ca                	mov    %ecx,%edx
  34:	eb 0a                	jmp    0x40
  36:	90                   	nop
  37:	90                   	nop
  38:	90                   	nop
  39:	90                   	nop
  3a:	90                   	nop
  3b:	90                   	nop
  3c:	90                   	nop
  3d:	90                   	nop
  3e:	90                   	nop
  3f:	90                   	nop

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/30 05:19 linux-6.1.y dcbcab9d7079 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf inconsistent lock state in kernfs_path_from_node
* Struck through repros no longer work on HEAD.