syzbot

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc6-syzkaller-00169-g906bd684e4b1 #0 Not tainted
------------------------------------------------------
syz.8.2296/17398 is trying to acquire lock:
ffff8880b8629598 (krc.lock){..-.}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline]
ffff8880b8629598 (krc.lock){..-.}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3725 [inline]
ffff8880b8629598 (krc.lock){..-.}-{2:2}, at: kvfree_call_rcu+0xda/0xbe0 kernel/rcu/tree.c:3811

but task is already holding lock:
ffff8880b862a858 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5d/0x220 kernel/time/timer.c:1051

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&base->lock){-.-.}-{2:2}:
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
       lock_timer_base+0x5d/0x220 kernel/time/timer.c:1051
       __mod_timer+0x426/0xdc0 kernel/time/timer.c:1132
       add_timer_global+0x8a/0xc0 kernel/time/timer.c:1330
       __queue_delayed_work+0x1ba/0x2e0 kernel/workqueue.c:2523
       queue_delayed_work_on+0x12a/0x150 kernel/workqueue.c:2552
       kvfree_call_rcu+0x749/0xbe0 kernel/rcu/tree.c:3839
       pwq_release_workfn+0x4dd/0xa50 kernel/workqueue.c:5078
       kthread_worker_fn+0x308/0xba0 kernel/kthread.c:844
       kthread+0x2c4/0x3a0 kernel/kthread.c:389
       ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 (krc.lock){..-.}-{2:2}:
       check_prev_add kernel/locking/lockdep.c:3161 [inline]
       check_prevs_add kernel/locking/lockdep.c:3280 [inline]
       validate_chain kernel/locking/lockdep.c:3904 [inline]
       __lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
       lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3725 [inline]
       kvfree_call_rcu+0xda/0xbe0 kernel/rcu/tree.c:3811
       trie_delete_elem+0x5c5/0x820 kernel/bpf/lpm_trie.c:540
       bpf_prog_2e5e7763945ac34e+0x45/0x4d
       bpf_dispatcher_nop_func include/linux/bpf.h:1265 [inline]
       __bpf_prog_run include/linux/filter.h:701 [inline]
       bpf_prog_run include/linux/filter.h:708 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2316 [inline]
       bpf_trace_run2+0x234/0x590 kernel/trace/bpf_trace.c:2357
       __bpf_trace_timer_start+0xc7/0x100 include/trace/events/timer.h:52
       __traceiter_timer_start+0x67/0xb0 include/trace/events/timer.h:52
       trace_timer_start include/trace/events/timer.h:52 [inline]
       enqueue_timer+0x2b4/0x550 kernel/time/timer.c:663
       internal_add_timer kernel/time/timer.c:688 [inline]
       __mod_timer+0x8d7/0xdc0 kernel/time/timer.c:1183
       sk_reset_timer+0x21/0xc0 net/core/sock.c:3508
       tipc_sk_finish_conn+0x183/0x790 net/tipc/socket.c:1671
       tipc_socketpair+0x364/0x470 net/tipc/socket.c:3347
       __sys_socketpair+0x2f3/0x5a0 net/socket.c:1796
       __do_sys_socketpair net/socket.c:1832 [inline]
       __se_sys_socketpair net/socket.c:1829 [inline]
       __x64_sys_socketpair+0x96/0x100 net/socket.c:1829
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&base->lock);
                               lock(krc.lock);
                               lock(&base->lock);
  lock(krc.lock);

 *** DEADLOCK ***

2 locks held by syz.8.2296/17398:
 #0: ffff8880b862a858 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x5d/0x220 kernel/time/timer.c:1051
 #1: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #1: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #1: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2315 [inline]
 #1: ffffffff8e1b8340 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x1c2/0x590 kernel/trace/bpf_trace.c:2357

stack backtrace:
CPU: 0 UID: 0 PID: 17398 Comm: syz.8.2296 Not tainted 6.12.0-rc6-syzkaller-00169-g906bd684e4b1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_circular_bug+0x41c/0x610 kernel/locking/lockdep.c:2074
 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
 check_prev_add kernel/locking/lockdep.c:3161 [inline]
 check_prevs_add kernel/locking/lockdep.c:3280 [inline]
 validate_chain kernel/locking/lockdep.c:3904 [inline]
 __lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 krc_this_cpu_lock kernel/rcu/tree.c:3312 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3725 [inline]
 kvfree_call_rcu+0xda/0xbe0 kernel/rcu/tree.c:3811
 trie_delete_elem+0x5c5/0x820 kernel/bpf/lpm_trie.c:540
 bpf_prog_2e5e7763945ac34e+0x45/0x4d
 bpf_dispatcher_nop_func include/linux/bpf.h:1265 [inline]
 __bpf_prog_run include/linux/filter.h:701 [inline]
 bpf_prog_run include/linux/filter.h:708 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2316 [inline]
 bpf_trace_run2+0x234/0x590 kernel/trace/bpf_trace.c:2357
 __bpf_trace_timer_start+0xc7/0x100 include/trace/events/timer.h:52
 __traceiter_timer_start+0x67/0xb0 include/trace/events/timer.h:52
 trace_timer_start include/trace/events/timer.h:52 [inline]
 enqueue_timer+0x2b4/0x550 kernel/time/timer.c:663
 internal_add_timer kernel/time/timer.c:688 [inline]
 __mod_timer+0x8d7/0xdc0 kernel/time/timer.c:1183
 sk_reset_timer+0x21/0xc0 net/core/sock.c:3508
 tipc_sk_finish_conn+0x183/0x790 net/tipc/socket.c:1671
 tipc_socketpair+0x364/0x470 net/tipc/socket.c:3347
 __sys_socketpair+0x2f3/0x5a0 net/socket.c:1796
 __do_sys_socketpair net/socket.c:1832 [inline]
 __se_sys_socketpair net/socket.c:1829 [inline]
 __x64_sys_socketpair+0x96/0x100 net/socket.c:1829
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa98937e719
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa98a0e8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000035
RAX: ffffffffffffffda RBX: 00007fa989535f80 RCX: 00007fa98937e719
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 000000000000001e
RBP: 00007fa9893f139e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000940 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa989535f80 R15: 00007fff6db00fc8
 </TASK>