==================================================================
BUG: KCSAN: data-race in complete_signal / do_signal_stop

read-write to 0xffff88804b96a064 of 4 bytes by task 4192 on cpu 1:
 freezer_count include/linux/freezer.h:121 [inline]
 freezable_schedule include/linux/freezer.h:173 [inline]
 do_signal_stop+0x552/0x6b0 kernel/signal.c:2395
 get_signal+0xa83/0x1510 kernel/signal.c:2717
 arch_do_signal+0x25/0x260 arch/x86/kernel/signal.c:811
 exit_to_user_mode_loop kernel/entry/common.c:161 [inline]
 exit_to_user_mode_prepare+0xde/0x170 kernel/entry/common.c:191
 irqentry_exit_to_user_mode+0x5/0x20 kernel/entry/common.c:279
 irqentry_exit+0xe/0x40 kernel/entry/common.c:367
 sysvec_apic_timer_interrupt+0x80/0x90 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631

read to 0xffff88804b96a064 of 4 bytes by interrupt on cpu 0:
 wants_signal kernel/signal.c:977 [inline]
 complete_signal+0x7b/0x5f0 kernel/signal.c:1000
 send_sigqueue+0x248/0x400 kernel/signal.c:1880
 posix_timer_event kernel/time/posix-timers.c:354 [inline]
 posix_timer_fn+0xdd/0x1f0 kernel/time/posix-timers.c:380
 __run_hrtimer+0x133/0x420 kernel/time/hrtimer.c:1524
 __hrtimer_run_queues kernel/time/hrtimer.c:1588 [inline]
 hrtimer_interrupt+0x36e/0xa10 kernel/time/hrtimer.c:1650
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0x6f/0x200 arch/x86/kernel/apic/apic.c:1097
 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:91 [inline]
 sysvec_apic_timer_interrupt+0x6f/0x90 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
 check_access kernel/kcsan/core.c:625 [inline]
 __tsan_read4+0xe9/0x180 kernel/kcsan/core.c:841
 nf_nat_ipv4_in+0x59/0x210 net/netfilter/nf_nat_proto.c:653
 nf_hook_entry_hookfn include/linux/netfilter.h:136 [inline]
 nf_hook_slow+0x72/0x170 net/netfilter/core.c:589
 nf_hook include/linux/netfilter.h:256 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip_rcv+0x237/0x250 net/ipv4/ip_input.c:539
 __netif_receive_skb_one_core net/core/dev.c:5315 [inline]
 __netif_receive_skb+0x8b/0x1b0 net/core/dev.c:5429
 process_backlog+0x23f/0x3d0 net/core/dev.c:6319
 napi_poll+0x178/0x4c0 net/core/dev.c:6763
 net_rx_action+0x17a/0x480 net/core/dev.c:6833
 __do_softirq+0x12c/0x2b1 kernel/softirq.c:298
 asm_call_irq_on_stack+0xf/0x20
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0x32/0x40 arch/x86/kernel/irq_64.c:77
 do_softirq kernel/softirq.c:343 [inline]
 __local_bh_enable_ip+0xba/0xd0 kernel/softirq.c:195
 local_bh_enable+0x1b/0x20 include/linux/bottom_half.h:32
 rcu_read_unlock_bh include/linux/rcupdate.h:730 [inline]
 ip_finish_output2+0xb10/0xba0 net/ipv4/ip_output.c:231
 __ip_finish_output+0x3d8/0x430 net/ipv4/ip_output.c:308
 ip_finish_output+0x39/0x160 net/ipv4/ip_output.c:318
 NF_HOOK_COND include/linux/netfilter.h:290 [inline]
 ip_output+0xf6/0x1a0 net/ipv4/ip_output.c:432
 dst_output include/net/dst.h:443 [inline]
 ip_local_out net/ipv4/ip_output.c:126 [inline]
 __ip_queue_xmit+0x9ca/0x9f0 net/ipv4/ip_output.c:532
 ip_queue_xmit+0x34/0x40 net/ipv4/ip_output.c:546
 __tcp_transmit_skb+0x1250/0x1860 net/ipv4/tcp_output.c:1404
 tcp_transmit_skb net/ipv4/tcp_output.c:1422 [inline]
 tcp_connect+0x56a/0xff0 net/ipv4/tcp_output.c:3849
 tcp_v4_connect+0xac7/0xba0 net/ipv4/tcp_ipv4.c:312
 __inet_stream_connect+0x586/0x690 net/ipv4/af_inet.c:661
 inet_stream_connect+0x44/0x70 net/ipv4/af_inet.c:725
 rds_tcp_conn_path_connect+0x360/0x430 net/rds/tcp_connect.c:172
 rds_connect_worker+0x125/0x1a0 net/rds/threads.c:176
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1fa/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26 Comm: kworker/u4:2 Not tainted 5.10.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krdsd rds_connect_worker
==================================================================