BUG: soft lockup in sock_close

Status: upstream: reported C repro on 2024/12/23 18:51
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+bb721a1495edb233298b@syzkaller.appspotmail.com
First crash: 668d, last: 11d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/02/02 linux-6.1.y (ToT) cd9b81672742 C [report] INFO: rcu detected stall in corrupted
2026/02/02 upstream (ToT) 18f7fcd5e69a C Didn't crash
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 BUG: soft lockup in sock_close 1 syz, C 201 3d19h 941d 0/2 upstream: reported C repro on 2024/03/25 07:28
linux-5.15 INFO: rcu detected stall in sock_close (3) origin:upstream 1 syz, C error 21 31d 885d 0/3 upstream: reported C repro on 2024/05/20 00:06
android-5-15 BUG: soft lockup in sock_close origin:downstream 1 syz, C done 388 10d 939d 0/2 upstream: reported C repro on 2024/03/26 23:21
upstream INFO: rcu detected stall in sock_close (5) prio:normal tipc 1 syz, C error error 91 87d 463d 0/29 upstream: reported C repro on 2025/07/16 17:01
android-6-1 BUG: soft lockup in sock_close origin:downstream 1 syz, C error 17 41d 939d 0/2 upstream: reported C repro on 2024/03/27 04:09
linux-5.15 INFO: rcu detected stall in sock_close (2) 1 1 1002d 1002d 0/3 auto-obsoleted due to no activity on 2024/05/03 14:38
upstream INFO: rcu detected stall in sock_close (4) net 1 2 1092d 1129d 0/29 auto-obsoleted due to no activity on 2024/01/24 15:51
linux-6.1 INFO: rcu detected stall in sock_close (3) 1 1 892d 892d 0/3 auto-obsoleted due to no activity on 2024/08/21 03:02
linux-6.1 INFO: rcu detected stall in sock_close origin:upstream 1 syz, C done 1 1200d 1200d 3/3 fixed on 2023/09/23 10:26
linux-6.1 INFO: rcu detected stall in sock_close (2) 1 1 994d 994d 0/3 auto-obsoleted due to no activity on 2024/05/11 05:25
upstream INFO: rcu detected stall in sock_close (3) tipc 1 syz, C done done 5 1802d 2296d 0/29 closed as invalid on 2022/02/08 10:42
linux-5.15 INFO: rcu detected stall in sock_close 1 syz, C error 2 1180d 1234d 0/3 auto-obsoleted due to no activity on 2023/11/07 13:02
linux-6.6 INFO: rcu detected stall in sock_close (2) origin:upstream 1 syz 2 9d19h 160d 0/2 upstream: reported syz repro on 2026/05/15 05:06
linux-6.6 INFO: rcu detected stall in sock_close 1 syz error 2 340d 423d 0/2 auto-obsoleted due to no activity on 2026/02/24 12:42
upstream INFO: rcu detected stall in sock_close cgroups mm 1 6 2514d 2515d 0/29 closed as invalid on 2019/12/04 14:04
upstream INFO: rcu detected stall in sock_close (2) cgroups mm 1 1 2479d 2479d 0/29 closed as invalid on 2020/01/09 08:13
▶ ▼ Fix bisection attempts (6)
Created Duration User Patch Repo Result
2026/06/26 12:44 2h37m fix candidate upstream OK (0) job log
2026/05/20 10:41 1h21m fix candidate upstream error job log
2026/04/03 06:00 1m fix candidate upstream error job log
2026/03/04 05:16 18m fix candidate upstream error job log
2026/02/02 05:15 1m fix candidate upstream error job log
2025/03/07 06:02 19m bisect fix linux-6.1.y error job log

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 0-.... } 2636 jiffies s: 3701 root: 0x1/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4408 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
RIP: 0010:__kasan_check_write+0x0/0x10 mm/kasan/shadow.c:37
Code: 8c eb 0a 48 c7 c7 75 f9 46 8c 48 89 de e8 78 02 55 08 31 ed eb d7 00 00 cc cc 89 f6 48 8b 0c 24 31 d2 e9 c3 ec ff ff 0f 1f 00 <89> f6 48 8b 0c 24 ba 01 00 00 00 e9 b0 ec ff ff 55 41 56 53 48 89
RSP: 0018:ffffc900000072c0 EFLAGS: 00000046
RAX: ffffffff818ea3f9 RBX: ffff8880b8c3bbb0 RCX: ffff8880262dda00
RDX: 0000000000000100 RSI: 0000000000000004 RDI: ffff8880b8c3bbb8
RBP: 0000000000000000 R08: ffffffff8f00d22f R09: 1ffffffff1e01a45
R10: dffffc0000000000 R11: fffffbfff1e01a46 R12: dffffc0000000000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b8c3bbb8
FS:  0000555559903500(0000) GS:ffff8880b8c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1082def158 CR3: 0000000059b99000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
 atomic_fetch_or include/linux/atomic/atomic-instrumented.h:406 [inline]
 irq_work_claim kernel/irq_work.c:59 [inline]
 irq_work_queue_on+0xaa/0x260 kernel/irq_work.c:137
 rcu_read_unlock_special+0x3c9/0x510 kernel/rcu/tree_plugin.h:678
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 trace_call_bpf+0x5bb/0x6b0 kernel/trace/bpf_trace.c:137
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:10037
 perf_trace_preemptirq_template+0x268/0x320 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0xd3/0x140 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x24/0x40 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:728
RIP: 0010:rcu_read_unlock_special+0x7f/0x510 kernel/rcu/tree_plugin.h:685
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 d2 68 95 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc90000007760 EFLAGS: 00000206
RAX: 73dc52b585414200 RBX: 1ffff92000000ef4 RCX: 73dc52b585414200
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf71a0
RBP: ffffc90000007860 R08: ffffffff9193434f R09: 1ffffffff2326869
R10: dffffc0000000000 R11: fffffbfff232686a R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8c3bb00 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 ndisc_send_skb+0xdc2/0x1520 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x367/0x640 net/ipv6/addrconf.c:3994
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x13e/0x1c0 kernel/softirq.c:428
Code: 8a e8 e6 b2 e4 08 65 66 8b 05 9e 65 b4 7e 66 85 c0 75 54 bf 01 00 00 00 e8 cf 82 09 00 e8 ba 72 39 00 fb 65 8b 05 8a 32 b3 7e <85> c0 75 05 e8 99 46 b1 ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc90004397c60 EFLAGS: 00000286
RAX: 0000000080000000 RBX: 0000000000000200 RCX: 73dc52b585414200
RDX: dffffc0000000000 RSI: ffffffff8a8c19a0 RDI: ffffffff8adf71a0
RBP: ffffc90004397ce8 R08: ffffffff91934307 R09: 1ffffffff2326860
R10: dffffc0000000000 R11: fffffbfff2326861 R12: ffffffff88bae7b3
R13: dffffc0000000000 R14: dffffc0000000000 R15: 1ffff92000872f8c
 tcp_close+0x24/0x110 net/ipv4/tcp.c:3082
 inet_release+0x139/0x180 net/ipv4/af_inet.c:430
 __sock_release net/socket.c:654 [inline]
 sock_close+0xbf/0x210 net/socket.c:1400
 __fput+0x20a/0x8b0 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:180
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:213
 __syscall_exit_to_user_mode_work kernel/entry/common.c:295 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:306
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1082b5ea0e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffe6e94d5d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000555559903500 RCX: 00007f1082b5ea0e
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffe6e94d67c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000001b
R13: 00000000000927c0 R14: 000000000001ab87 R15: 00007ffe6e94d6d0
 </TASK>

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/11 04:05 linux-6.1.y a500ba24937a 4f92358f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2026/02/01 23:46 linux-6.1.y cd9b81672742 6b8752f2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2024/12/23 18:50 linux-6.1.y 29f02ec58a94 b4fbdbd4 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: soft lockup in sock_close
2026/09/14 10:25 linux-6.1.y cf82dcca9634 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2026/06/20 21:53 linux-6.1.y fdb6fcb41cc7 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2026/05/03 03:07 linux-6.1.y 4931e0e1673d a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2026/05/02 01:39 linux-6.1.y 4931e0e1673d 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2026/04/27 06:08 linux-6.1.y 7c87defbd336 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2026/01/27 17:55 linux-6.1.y cd9b81672742 9a514c2f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
2025/11/10 17:24 linux-6.1.y f6e38ae624cf 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sock_close
* Struck through repros no longer work on HEAD.