=========================[  631.240319][ T9836] ============================================
WARNING: possible recursive locking detected
syzkaller #0 Tainted: G             L     
--------------------------------------------
kworker/u8:16/9836 is trying to acquire lock:
ffff888061305358 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline]
ffff888061305358 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: inet6_getname+0x15d/0x650 net/ipv6/af_inet6.c:533

but task is already holding lock:
ffff888061305358 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline]
ffff888061305358 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: rds_tcp_recv_path+0xfe/0x340 net/rds/tcp_recv.c:304

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

       CPU0
       ----
  lock(k-sk_lock-AF_INET6);
  lock(k-sk_lock-AF_INET6);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

7 locks held by kworker/u8:16/9836:
 #0: ffff88802a0d2138 ((wq_completion)krds_cp_wq#1/0){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3250 [inline]
 #0: ffff88802a0d2138 ((wq_completion)krds_cp_wq#1/0){+.+.}-{0:0}, at: process_scheduled_works+0x9ea/0x1830 kernel/workqueue.c:3358
 #1: ffffc900063a7c40 ((work_completion)(&(&cp->cp_recv_w)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3251 [inline]
 #1: ffffc900063a7c40 ((work_completion)(&(&cp->cp_recv_w)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa25/0x1830 kernel/workqueue.c:3358
 #2: ffff888061305358 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1709 [inline]
 #2: ffff888061305358 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: rds_tcp_recv_path+0xfe/0x340 net/rds/tcp_recv.c:304
 #3: ffffffff8dc64fa0 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #4: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
 #5: ffff888061305590 (k-clock-AF_INET6){++..}-{3:3}, at: read_lock_bh include/linux/rwlock_rt.h:45 [inline]
 #5: ffff888061305590 (k-clock-AF_INET6){++..}-{3:3}, at: rds_tcp_data_ready+0x127/0x8e0 net/rds/tcp_recv.c:320
 #6: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
 #6: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
 #6: ffffffff8ddcd780 (rcu_read_lock){....}-{1:3}, at: rt_read_lock+0x277/0x4b0 kernel/locking/spinlock_rt.c:234

stack backtrace:
CPU: 0 UID: 0 PID: 9836 Comm: kworker/u8:16 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: krds_cp_wq#1/0 rds_recv_worker
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_deadlock_bug+0x279/0x290 kernel/locking/lockdep.c:3041
 check_deadlock kernel/locking/lockdep.c:3093 [inline]
 validate_chain kernel/locking/lockdep.c:3895 [inline]
 __lock_acquire+0x253f/0x2cf0 kernel/locking/lockdep.c:5237
 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868
 lock_sock_nested+0x3e/0x130 net/core/sock.c:3780
 lock_sock include/net/sock.h:1709 [inline]
 inet6_getname+0x15d/0x650 net/ipv6/af_inet6.c:533
 rds_tcp_get_peer_sport net/rds/tcp_listen.c:70 [inline]
 rds_tcp_conn_slots_available+0x288/0x470 net/rds/tcp_listen.c:149
 rds_recv_hs_exthdrs+0x64f/0x800 net/rds/recv.c:265
 rds_recv_incoming+0x9f6/0x12e0 net/rds/recv.c:389
 rds_tcp_data_recv+0x816/0xa40 net/rds/tcp_recv.c:243
 __tcp_read_sock+0x196/0x970 net/ipv4/tcp.c:1702
 rds_tcp_read_sock net/rds/tcp_recv.c:277 [inline]
 rds_tcp_data_ready+0x32d/0x8e0 net/rds/tcp_recv.c:331
 tcp_data_queue+0x1e2e/0x5e50 net/ipv4/tcp_input.c:5719
 tcp_rcv_established+0xf45/0x2740 net/ipv4/tcp_input.c:6710
 tcp_v6_do_rcv+0x88b/0x1ac0 net/ipv6/tcp_ipv6.c:1609
 sk_backlog_rcv include/net/sock.h:1185 [inline]
 __release_sock+0x20b/0x3d0 net/core/sock.c:3213
 release_sock+0x75/0x210 net/core/sock.c:3795
 rds_tcp_recv_path+0x2ee/0x340 net/rds/tcp_recv.c:306
 rds_recv_worker+0xc6/0x310 net/rds/threads.c:226
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
BUG: sleeping function called from invalid context at net/core/sock.c:3782
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 9836, name: kworker/u8:16
preempt_count: 0, expected: 0
RCU nest depth: 2, expected: 0
INFO: lockdep is turned off.
CPU: 0 UID: 0 PID: 9836 Comm: kworker/u8:16 Tainted: G             L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: krds_cp_wq#1/0 rds_recv_worker
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 __might_resched+0x329/0x480 kernel/sched/core.c:8884
 lock_sock_nested+0x53/0x130 net/core/sock.c:3782
 lock_sock include/net/sock.h:1709 [inline]
 inet6_getname+0x15d/0x650 net/ipv6/af_inet6.c:533
 rds_tcp_get_peer_sport net/rds/tcp_listen.c:70 [inline]
 rds_tcp_conn_slots_available+0x288/0x470 net/rds/tcp_listen.c:149
 rds_recv_hs_exthdrs+0x64f/0x800 net/rds/recv.c:265
 rds_recv_incoming+0x9f6/0x12e0 net/rds/recv.c:389
 rds_tcp_data_recv+0x816/0xa40 net/rds/tcp_recv.c:243
 __tcp_read_sock+0x196/0x970 net/ipv4/tcp.c:1702
 rds_tcp_read_sock net/rds/tcp_recv.c:277 [inline]
 rds_tcp_data_ready+0x32d/0x8e0 net/rds/tcp_recv.c:331
 tcp_data_queue+0x1e2e/0x5e50 net/ipv4/tcp_input.c:5719
 tcp_rcv_established+0xf45/0x2740 net/ipv4/tcp_input.c:6710
 tcp_v6_do_rcv+0x88b/0x1ac0 net/ipv6/tcp_ipv6.c:1609
 sk_backlog_rcv include/net/sock.h:1185 [inline]
 __release_sock+0x20b/0x3d0 net/core/sock.c:3213
 release_sock+0x75/0x210 net/core/sock.c:3795
 rds_tcp_recv_path+0x2ee/0x340 net/rds/tcp_recv.c:306
 rds_recv_worker+0xc6/0x310 net/rds/threads.c:226
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0xcac/0xf40 kernel/rcu/tree_plugin.h:332, CPU#0: kworker/u8:16/9836
Modules linked in:
CPU: 0 UID: 0 PID: 9836 Comm: kworker/u8:16 Tainted: G        W    L      syzkaller #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN, [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: krds_cp_wq#1/0 rds_recv_worker
RIP: 0010:rcu_note_context_switch+0xcac/0xf40 kernel/rcu/tree_plugin.h:332
Code: 00 41 c6 45 00 00 48 8b 3d 11 c7 bf 0d 48 81 c4 b8 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d e9 8b 62 ff ff 48 8d 3d 14 84 c3 0d <67> 48 0f b9 3a e9 1b f4 ff ff 90 0f 0b 90 45 84 e4 0f 84 ea f3 ff
RSP: 0018:ffffc900063a6a70 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff888037cc3c80 RCX: 0000000080000002
RDX: 0000000000000000 RSI: ffffffff8ba643e0 RDI: ffffffff8f6d8fd0
RBP: dffffc0000000000 R08: ffffffff8f6a25b7 R09: 1ffffffff1ed44b6
R10: dffffc0000000000 R11: fffffbfff1ed44b7 R12: 0000000000000000
R13: 0000000000000000 R14: ffff8880b883cb80 R15: ffff888037cc4104
FS:  0000000000000000(0000) GS:ffff888126343000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f03169b7dac CR3: 0000000028cb6000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __schedule+0x2b0/0x52c0 kernel/sched/core.c:6791
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7004
 __lock_sock+0x175/0x2e0 net/core/sock.c:3188
 lock_sock_nested+0xb3/0x130 net/core/sock.c:3785
 lock_sock include/net/sock.h:1709 [inline]
 inet6_getname+0x15d/0x650 net/ipv6/af_inet6.c:533
 rds_tcp_get_peer_sport net/rds/tcp_listen.c:70 [inline]
 rds_tcp_conn_slots_available+0x288/0x470 net/rds/tcp_listen.c:149
 rds_recv_hs_exthdrs+0x64f/0x800 net/rds/recv.c:265
 rds_recv_incoming+0x9f6/0x12e0 net/rds/recv.c:389
 rds_tcp_data_recv+0x816/0xa40 net/rds/tcp_recv.c:243
 __tcp_read_sock+0x196/0x970 net/ipv4/tcp.c:1702
 rds_tcp_read_sock net/rds/tcp_recv.c:277 [inline]
 rds_tcp_data_ready+0x32d/0x8e0 net/rds/tcp_recv.c:331
 tcp_data_queue+0x1e2e/0x5e50 net/ipv4/tcp_input.c:5719
 tcp_rcv_established+0xf45/0x2740 net/ipv4/tcp_input.c:6710
 tcp_v6_do_rcv+0x88b/0x1ac0 net/ipv6/tcp_ipv6.c:1609
 sk_backlog_rcv include/net/sock.h:1185 [inline]
 __release_sock+0x20b/0x3d0 net/core/sock.c:3213
 release_sock+0x75/0x210 net/core/sock.c:3795
 rds_tcp_recv_path+0x2ee/0x340 net/rds/tcp_recv.c:306
 rds_recv_worker+0xc6/0x310 net/rds/threads.c:226
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 41 c6             	add    %al,-0x3a(%rcx)
   3:	45 00 00             	add    %r8b,(%r8)
   6:	48 8b 3d 11 c7 bf 0d 	mov    0xdbfc711(%rip),%rdi        # 0xdbfc71e
   d:	48 81 c4 b8 00 00 00 	add    $0xb8,%rsp
  14:	5b                   	pop    %rbx
  15:	41 5c                	pop    %r12
  17:	41 5d                	pop    %r13
  19:	41 5e                	pop    %r14
  1b:	41 5f                	pop    %r15
  1d:	5d                   	pop    %rbp
  1e:	e9 8b 62 ff ff       	jmp    0xffff62ae
  23:	48 8d 3d 14 84 c3 0d 	lea    0xdc38414(%rip),%rdi        # 0xdc3843e
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 1b f4 ff ff       	jmp    0xfffff44f
  34:	90                   	nop
  35:	0f 0b                	ud2
  37:	90                   	nop
  38:	45 84 e4             	test   %r12b,%r12b
  3b:	0f                   	.byte 0xf
  3c:	84 ea                	test   %ch,%dl
  3e:	f3                   	repz
  3f:	ff                   	.byte 0xff