======================================================
WARNING: possible circular locking dependency detected
6.11.0-rc5-syzkaller-00155-ga3c1e45156ad #0 Not tainted
------------------------------------------------------
sshd/5231 is trying to acquire lock:
ffff8880b8829430 (krc.lock){....}-{2:2}, at: krc_this_cpu_lock kernel/rcu/tree.c:3332 [inline]
ffff8880b8829430 (krc.lock){....}-{2:2}, at: add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3731 [inline]
ffff8880b8829430 (krc.lock){....}-{2:2}, at: kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3816

but task is already holding lock:
ffff8880b882a718 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x744/0xeb0 kernel/time/timer.c:1164

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&base->lock){-.-.}-{2:2}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       lock_timer_base+0x112/0x240 kernel/time/timer.c:1051
       __mod_timer+0x1ca/0xeb0 kernel/time/timer.c:1132
       queue_delayed_work_on+0x1ca/0x390 kernel/workqueue.c:2554
       kvfree_call_rcu+0x47f/0x790 kernel/rcu/tree.c:3844
       pwq_release_workfn+0x6d1/0x860 kernel/workqueue.c:5066
       kthread_worker_fn+0x500/0xaf0 kernel/kthread.c:842
       kthread+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/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:3133 [inline]
       check_prevs_add kernel/locking/lockdep.c:3252 [inline]
       validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
       __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
       __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:3332 [inline]
       add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3731 [inline]
       kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3816
       trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540
       bpf_prog_2c29ac5cdc6b1842+0x42/0x46
       bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline]
       __bpf_prog_run include/linux/filter.h:691 [inline]
       bpf_prog_run include/linux/filter.h:698 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2406 [inline]
       bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2447
       trace_timer_start include/trace/events/timer.h:52 [inline]
       enqueue_timer+0x3ce/0x570 kernel/time/timer.c:663
       internal_add_timer kernel/time/timer.c:688 [inline]
       __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183
       sk_reset_timer+0x23/0xc0 net/core/sock.c:3440
       tcp_event_new_data_sent+0x203/0x360 net/ipv4/tcp_output.c:83
       tcp_write_xmit+0x18dc/0x6a10 net/ipv4/tcp_output.c:2836
       __tcp_push_pending_frames+0x9b/0x360 net/ipv4/tcp_output.c:3014
       tcp_sendmsg_locked+0x43b1/0x4e10 net/ipv4/tcp.c:1322
       tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1354
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg+0x1a6/0x270 net/socket.c:745
       sock_write_iter+0x2dd/0x400 net/socket.c:1160
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0xa72/0xc90 fs/read_write.c:590
       ksys_write+0x1a0/0x2c0 fs/read_write.c:643
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 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 ***

3 locks held by sshd/5231:
 #0: ffff88807eb7b358 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline]
 #0: ffff88807eb7b358 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x22/0x50 net/ipv4/tcp.c:1353
 #1: ffff8880b882a718 (&base->lock){-.-.}-{2:2}, at: __mod_timer+0x744/0xeb0 kernel/time/timer.c:1164
 #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline]
 #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2405 [inline]
 #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x1fc/0x540 kernel/trace/bpf_trace.c:2447

stack backtrace:
CPU: 0 UID: 0 PID: 5231 Comm: sshd Not tainted 6.11.0-rc5-syzkaller-00155-ga3c1e45156ad #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2186
 check_prev_add kernel/locking/lockdep.c:3133 [inline]
 check_prevs_add kernel/locking/lockdep.c:3252 [inline]
 validate_chain+0x18e0/0x5900 kernel/locking/lockdep.c:3868
 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759
 __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:3332 [inline]
 add_ptr_to_bulk_krc_lock kernel/rcu/tree.c:3731 [inline]
 kvfree_call_rcu+0x18a/0x790 kernel/rcu/tree.c:3816
 trie_delete_elem+0x546/0x6a0 kernel/bpf/lpm_trie.c:540
 bpf_prog_2c29ac5cdc6b1842+0x42/0x46
 bpf_dispatcher_nop_func include/linux/bpf.h:1243 [inline]
 __bpf_prog_run include/linux/filter.h:691 [inline]
 bpf_prog_run include/linux/filter.h:698 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2406 [inline]
 bpf_trace_run2+0x2ec/0x540 kernel/trace/bpf_trace.c:2447
 trace_timer_start include/trace/events/timer.h:52 [inline]
 enqueue_timer+0x3ce/0x570 kernel/time/timer.c:663
 internal_add_timer kernel/time/timer.c:688 [inline]
 __mod_timer+0xa0e/0xeb0 kernel/time/timer.c:1183
 sk_reset_timer+0x23/0xc0 net/core/sock.c:3440
 tcp_event_new_data_sent+0x203/0x360 net/ipv4/tcp_output.c:83
 tcp_write_xmit+0x18dc/0x6a10 net/ipv4/tcp_output.c:2836
 __tcp_push_pending_frames+0x9b/0x360 net/ipv4/tcp_output.c:3014
 tcp_sendmsg_locked+0x43b1/0x4e10 net/ipv4/tcp.c:1322
 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1354
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x1a6/0x270 net/socket.c:745
 sock_write_iter+0x2dd/0x400 net/socket.c:1160
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa72/0xc90 fs/read_write.c:590
 ksys_write+0x1a0/0x2c0 fs/read_write.c:643
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fedbe516bf2
Code: 89 c7 48 89 44 24 08 e8 7b 34 fa ff 48 8b 44 24 08 48 83 c4 28 c3 c3 64 8b 04 25 18 00 00 00 85 c0 75 20 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 76 6f 48 8b 15 07 a2 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffe72813eb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000000002c RCX: 00007fedbe516bf2
RDX: 000000000000002c RSI: 00005597af666960 RDI: 0000000000000004
RBP: 00005597af674c20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000559786cfeaa4
R13: 0000000000000051 R14: 0000559786cff3e8 R15: 00007ffe72813f28
 </TASK>