=============================
[ BUG: Invalid wait context ]
syzkaller #0 Tainted: G L
-----------------------------
udevd/5641 is trying to lock:
ffff888058459bc8 (&gpc->lock){....}-{3:3}, at: kvm_xen_set_evtchn_fast+0x208/0x8d0 arch/x86/kvm/xen.c:1872
other info that might help us debug this:
context-{2:2}
locks held by udevd/5641: 5, last CPU#0:
#0: ffff888056db0f80 (&type->i_mutex_dir_key#4){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:1041 [inline]
#0: ffff888056db0f80 (&type->i_mutex_dir_key#4){++++}-{4:4}, at: lookup_open+0x221/0x1ae0 fs/namei.c:4466
#1: ffff888048d36c60 (DCACHE_PAR_LOOKUP#5){+.+.}-{0:0}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#1: ffff888048d36c60 (DCACHE_PAR_LOOKUP#5){+.+.}-{0:0}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#1: ffff888048d36c60 (DCACHE_PAR_LOOKUP#5){+.+.}-{0:0}, at: __d_alloc_parallel+0x39e/0x1700 fs/dcache.c:2891
#2: ffff88801d28c980 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_iop_lookup+0x5f/0x320 fs/kernfs/dir.c:1258
#3: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
#3: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#3: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
#3: ffffffff9015a260 (rcu_read_lock){....}-{1:3}, at: kernfs_root+0x1c/0x230 fs/kernfs/kernfs-internal.h:76
#4: ffff88805845a118 (&kvm->srcu){.?.?}-{0:0}, at: srcu_lock_acquire include/linux/srcu.h:249 [inline]
#4: ffff88805845a118 (&kvm->srcu){.?.?}-{0:0}, at: srcu_read_lock include/linux/srcu.h:356 [inline]
#4: ffff88805845a118 (&kvm->srcu){.?.?}-{0:0}, at: kvm_xen_set_evtchn_fast+0x1d2/0x8d0 arch/x86/kvm/xen.c:1870
stack backtrace:
CPU: 0 UID: 0 PID: 5641 Comm: udevd Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_lock_invalid_wait_context kernel/locking/lockdep.c:4874 [inline]
check_wait_context kernel/locking/lockdep.c:4946 [inline]
__lock_acquire+0xf5b/0x2de0 kernel/locking/lockdep.c:5238
lock_acquire+0x115/0x350 kernel/locking/lockdep.c:5942
__raw_read_lock_irqsave include/linux/rwlock_api_smp.h:174 [inline]
_raw_read_lock_irqsave+0x48/0x60 kernel/locking/spinlock.c:271
kvm_xen_set_evtchn_fast+0x208/0x8d0 arch/x86/kvm/xen.c:1872
xen_timer_callback+0x109/0x220 arch/x86/kvm/xen.c:139
__run_hrtimer kernel/time/hrtimer.c:2079 [inline]
__hrtimer_run_queues+0x371/0xa10 kernel/time/hrtimer.c:2136
hrtimer_interrupt+0x4cd/0xaa0 kernel/time/hrtimer.c:2255
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
__sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0x52/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:variable_ffs arch/x86/include/asm/bitops.h:312 [inline]
RIP: 0010:handle_softirqs+0x19f/0x8d0 kernel/softirq.c:657
Code: 6c 24 24 44 0f b7 f3 48 c7 c7 80 53 2b 8c e8 88 6c 7c 0a 65 66 c7 05 9a 17 58 13 00 00 e8 d9 05 48 00 fb 48 c7 c3 c0 a0 e0 8f ff ff ff ff 41 0f bc c6 41 89 c5 41 ff c5 0f 84 f9 03 00 00 48
RSP: 0000:ffffc90000007f38 EFLAGS: 00000206
RAX: 00000000002378de RBX: ffffffff8fe0a0c0 RCX: 8000000000000100
RDX: 0000000000000003 RSI: ffffffff8e6a8877 RDI: ffffffff8c8ea380
RBP: 000000000000000a R08: ffffffff91be00bf R09: 1ffffffff237c017
R10: dffffc0000000000 R11: fffffbfff237c018 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000004 R15: dffffc0000000000
__do_softirq kernel/softirq.c:703 [inline]
invoke_softirq kernel/softirq.c:542 [inline]
__irq_exit_rcu+0xc6/0x220 kernel/softirq.c:786
irq_exit_rcu+0x9/0x30 kernel/softirq.c:809
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:lock_acquire+0x232/0x350 kernel/locking/lockdep.c:5947
Code: ff ff ff e8 30 8e 61 0a f7 44 24 10 00 02 00 00 0f 84 38 ff ff ff 65 48 8b 05 32 58 3d 13 48 3b 44 24 50 75 33 fb 48 83 c4 58 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 4f a1 64 0a cc 48 8d 3d 07 23 1d
RSP: 0000:ffffc900042ff908 EFLAGS: 00000282
RAX: 666c516d311a8a00 RBX: 0000000000000000 RCX: 0000000000000046
RDX: 000000009d6af375 RSI: ffffffff8e93469d RDI: ffffffff8c8ea380
RBP: ffff88807ee65dc0 R08: ffffffff8282c89c R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed1003a51925 R12: ffffffff9015a260
R13: 0000000000000002 R14: 0000000000000000 R15: 0000000000000246
rcu_lock_acquire include/linux/rcupdate.h:309 [inline]
rcu_read_lock include/linux/rcupdate.h:849 [inline]
class_rcu_constructor include/linux/rcupdate.h:1216 [inline]
kernfs_root+0x38/0x230 fs/kernfs/kernfs-internal.h:76
kernfs_active fs/kernfs/dir.c:42 [inline]
kernfs_iop_lookup+0x15a/0x320 fs/kernfs/dir.c:1268
lookup_open+0xa54/0x1ae0 fs/namei.c:4536
open_last_lookups fs/namei.c:4774 [inline]
path_openat+0x70c/0x20f0 fs/namei.c:5013
do_file_open+0x23e/0x4a0 fs/namei.c:5045
do_sys_openat2+0x115/0x200 fs/open.c:1443
do_sys_open fs/open.c:1449 [inline]
__do_sys_openat fs/open.c:1465 [inline]
__se_sys_openat fs/open.c:1460 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1460
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe9736a7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff755f4cc0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe973da5880 RCX: 00007fe9736a7407
RDX: 0000000000080000 RSI: 00007fff755f4e40 RDI: ffffffffffffff9c
RBP: 0000000000000008 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000055fb6aedd7f5
R13: 000055fb6aedd7f5 R14: 0000000000000001 R15: 000055fb6aef8140
----------------
Code disassembly (best guess):
0: 6c insb (%dx),%es:(%rdi)
1: 24 24 and $0x24,%al
3: 44 0f b7 f3 movzwl %bx,%r14d
7: 48 c7 c7 80 53 2b 8c mov $0xffffffff8c2b5380,%rdi
e: e8 88 6c 7c 0a call 0xa7c6c9b
13: 65 66 c7 05 9a 17 58 movw $0x0,%gs:0x1358179a(%rip) # 0x135817b7
1a: 13 00 00
1d: e8 d9 05 48 00 call 0x4805fb
22: fb sti
23: 48 c7 c3 c0 a0 e0 8f mov $0xffffffff8fe0a0c0,%rbx
* 2a: b8 ff ff ff ff mov $0xffffffff,%eax <-- trapping instruction
2f: 41 0f bc c6 bsf %r14d,%eax
33: 41 89 c5 mov %eax,%r13d
36: 41 ff c5 inc %r13d
39: 0f 84 f9 03 00 00 je 0x438
3f: 48 rex.W