rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 0-....: (1 GPs behind) idle=bba/1/0x4000000000000002 softirq=60841/60842 fqs=5242
(detected by 1, t=10502 jiffies, g=102917, q=287)
============================================
WARNING: possible recursive locking detected
5.10.0-syzkaller #0 Not tainted
--------------------------------------------
systemd-udevd/4902 is trying to acquire lock:
ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: rcu_dump_cpu_stacks+0x9c/0x21e kernel/rcu/tree_stall.h:334
but task is already holding lock:
ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:493 [inline]
ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:652 [inline]
ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3751 [inline]
ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0xbc/0xec3 kernel/rcu/tree.c:2580
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(rcu_node_0);
lock(rcu_node_0);
*** DEADLOCK ***
May be due to missing lock nesting notation
3 locks held by systemd-udevd/4902:
#0: ffff888060de3bd0 (&type->i_mutex_dir_key#4){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:784 [inline]
#0: ffff888060de3bd0 (&type->i_mutex_dir_key#4){++++}-{3:3}, at: lookup_slow fs/namei.c:1560 [inline]
#0: ffff888060de3bd0 (&type->i_mutex_dir_key#4){++++}-{3:3}, at: walk_component+0x409/0x6a0 fs/namei.c:1861
#1: ffffffff8b33a020 (rcu_read_lock){....}-{1:2}, at: d_wait_lookup fs/dcache.c:2525 [inline]
#1: ffffffff8b33a020 (rcu_read_lock){....}-{1:2}, at: d_alloc_parallel+0x150/0x19b0 fs/dcache.c:2609
#2: ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: print_other_cpu_stall kernel/rcu/tree_stall.h:493 [inline]
#2: ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: check_cpu_stall kernel/rcu/tree_stall.h:652 [inline]
#2: ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: rcu_pending kernel/rcu/tree.c:3751 [inline]
#2: ffffffff8b342118 (rcu_node_0){-.-.}-{2:2}, at: rcu_sched_clock_irq.cold+0xbc/0xec3 kernel/rcu/tree.c:2580
stack backtrace:
CPU: 1 PID: 4902 Comm: systemd-udevd Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
print_deadlock_bug kernel/locking/lockdep.c:2761 [inline]
check_deadlock kernel/locking/lockdep.c:2804 [inline]
validate_chain kernel/locking/lockdep.c:3595 [inline]
__lock_acquire.cold+0x15e/0x3b0 kernel/locking/lockdep.c:4832
lock_acquire kernel/locking/lockdep.c:5437 [inline]
lock_acquire+0x29d/0x740 kernel/locking/lockdep.c:5402
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:159
rcu_dump_cpu_stacks+0x9c/0x21e kernel/rcu/tree_stall.h:334
print_other_cpu_stall kernel/rcu/tree_stall.h:510 [inline]
check_cpu_stall kernel/rcu/tree_stall.h:652 [inline]
rcu_pending kernel/rcu/tree.c:3751 [inline]
rcu_sched_clock_irq.cold+0x6db/0xec3 kernel/rcu/tree.c:2580
update_process_times+0x16d/0x200 kernel/time/timer.c:1782
tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1376
__run_hrtimer kernel/time/hrtimer.c:1519 [inline]
__hrtimer_run_queues+0x1ce/0xea0 kernel/time/hrtimer.c:1583
hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1645
local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
__sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1102
asm_call_irq_on_stack+0xf/0x20
__run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline]
run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline]
sysvec_apic_timer_interrupt+0xbd/0x100 arch/x86/kernel/apic/apic.c:1096
asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628
RIP: 0010:__sanitizer_cov_trace_pc+0x55/0x60 kernel/kcov.c:207
Code: 82 a8 14 00 00 83 f8 02 75 20 48 8b 8a b0 14 00 00 8b 92 ac 14 00 00 48 8b 01 48 83 c0 01 48 39 c2 76 07 48 89 34 c1 48 89 01 66 2e 0f 1f 84 00 00 00 00 00 41 55 41 54 49 89 fc 55 48 bd eb
RSP: 0018:ffffc9000112f8c0 EFLAGS: 00000293
RAX: 0000000000000000 RBX: fffffbfff1defbab RCX: ffffffff81c46e5a
RDX: ffff8880187cd040 RSI: ffffffff81c46e31 RDI: 0000000000000001
RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff8ef7dd5f
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
R13: dffffc0000000000 R14: 00000000e2b65537 R15: ffffffff8ef7dd58
rep_nop arch/x86/include/asm/vdso/processor.h:13 [inline]
cpu_relax arch/x86/include/asm/vdso/processor.h:18 [inline]
bit_spin_lock include/linux/bit_spinlock.h:30 [inline]
hlist_bl_lock include/linux/list_bl.h:148 [inline]
d_alloc_parallel+0xe91/0x19b0 fs/dcache.c:2576
__lookup_slow+0x193/0x480 fs/namei.c:1529
lookup_slow fs/namei.c:1561 [inline]
walk_component+0x418/0x6a0 fs/namei.c:1861
lookup_last fs/namei.c:2310 [inline]
path_lookupat+0x1ba/0x830 fs/namei.c:2334
filename_lookup+0x19f/0x560 fs/namei.c:2367
user_path_at include/linux/namei.h:59 [inline]
do_faccessat+0x129/0x820 fs/open.c:423
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fe689ace9c7
Code: 83 c4 08 48 3d 01 f0 ff ff 73 01 c3 48 8b 0d c8 d4 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 b8 15 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a1 d4 2b 00 f7 d8 64 89 01 48
RSP: 002b:00007ffe86a49b88 EFLAGS: 00000246 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 000055c90e020460 RCX: 00007fe689ace9c7
RDX: 00746e657665752f RSI: 0000000000000000 RDI: 00007ffe86a49b90
RBP: 00007ffe86a49c00 R08: 000000000000c480 R09: 0000000000001010
R10: 00007fe689d8cb58 R11: 0000000000000246 R12: 000055c90c7a8856
R13: 000055c90e02d7b0 R14: 00007ffe86a49b90 R15: 000055c90e01d9f0