syzbot


INFO: rcu detected stall in sys_getsockopt (2)

Status: upstream: reported C repro on 2025/03/21 07:27
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+19b96719a910448956cb@syzkaller.appspotmail.com
First crash: 367d, last: 3d14h
Fix bisection: failed (error log, bisect log)
  
Bug presence (2)
Date Name Commit Repro Result
2026/01/31 linux-6.1.y (ToT) cd9b81672742 C [report] INFO: rcu detected stall in corrupted
2026/01/30 upstream (ToT) 4d310797262f C Didn't crash
Similar bugs (20)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_getsockopt (2) mm 1 1 2267d 2267d 0/29 closed as invalid on 2020/01/08 05:23
linux-4.19 INFO: rcu detected stall in sys_getsockopt 1 1 1279d 1279d 0/1 auto-obsoleted due to no activity on 2023/01/19 05:52
upstream INFO: rcu detected stall in sys_getsockopt (11) netfilter 1 4 813d 825d 0/29 auto-obsoleted due to no activity on 2024/03/30 17:47
linux-5.15 INFO: rcu detected stall in sys_getsockopt 1 1 832d 832d 0/3 auto-obsoleted due to no activity on 2024/03/21 16:23
linux-5.15 INFO: rcu detected stall in sys_getsockopt (2) 1 2 483d 518d 0/3 auto-obsoleted due to no activity on 2025/03/05 03:25
upstream INFO: rcu detected stall in sys_getsockopt (3) mm 1 1 2266d 2266d 0/29 closed as invalid on 2020/01/08 05:33
linux-6.6 INFO: rcu detected stall in sys_getsockopt (2) 1 1 122d 122d 0/2 auto-obsoleted due to no activity on 2026/03/02 01:54
upstream INFO: rcu detected stall in sys_getsockopt (4) mm 1 3 2266d 2266d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_getsockopt (6) kvm 1 3 1684d 1752d 0/29 auto-closed as invalid on 2021/11/10 12:58
linux-6.6 INFO: rcu detected stall in sys_getsockopt 1 1 250d 250d 0/2 auto-obsoleted due to no activity on 2025/10/24 08:59
upstream INFO: rcu detected stall in sys_getsockopt (7) netfilter 1 2 1541d 1591d 0/29 closed as invalid on 2022/02/08 10:10
upstream INFO: rcu detected stall in sys_getsockopt (5) sctp 1 2 2084d 2127d 0/29 auto-closed as invalid on 2020/10/06 19:28
linux-6.1 INFO: rcu detected stall in sys_getsockopt 1 4 749d 907d 0/3 auto-obsoleted due to no activity on 2024/06/12 17:46
upstream INFO: rcu detected stall in sys_getsockopt (10) mm 1 9 944d 1026d 0/29 auto-obsoleted due to no activity on 2023/11/20 15:28
linux-5.15 BUG: soft lockup in sys_getsockopt 1 2 271d 292d 0/3 auto-obsoleted due to no activity on 2025/10/03 23:07
upstream INFO: rcu detected stall in sys_getsockopt (9) kernel 1 6 1147d 1303d 0/29 auto-obsoleted due to no activity on 2023/05/01 05:21
upstream INFO: rcu detected stall in sys_getsockopt (8) net 1 2 1432d 1447d 0/29 auto-closed as invalid on 2022/07/21 00:25
upstream INFO: rcu detected stall in sys_getsockopt mm 1 2 2301d 2301d 0/29 closed as invalid on 2019/12/04 14:04
android-54 BUG: soft lockup in sys_getsockopt 1 1 706d 706d 0/2 auto-obsoleted due to no activity on 2024/07/15 21:19
android-5-15 BUG: soft lockup in sys_getsockopt 1 6 601d 699d 0/2 auto-obsoleted due to no activity on 2024/10/28 21:41
Fix bisection attempts (5)
Created Duration User Patch Repo Result
2026/03/02 21:43 1m fix candidate upstream error job log
2026/01/31 18:09 1m fix candidate upstream error job log
2026/01/07 03:44 1h47m fix candidate upstream OK (0) job log
2025/06/27 15:32 16m fix candidate upstream error job log
2025/05/31 07:47 18m bisect fix linux-6.1.y error job log

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2648 jiffies s: 3641 root: 0x2/.
rcu: blocking rcu_node structures (internal RCU debug):
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4385 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__sanitizer_cov_trace_pc+0x58/0x60 kernel/kcov.c:234
Code: f8 15 00 00 83 fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc 15 00 00 48 39 cf 73 08 48 89 3a 48 89 44 f2 08 <c3> 0f 1f 80 00 00 00 00 48 8b 04 24 65 48 8b 15 24 fc 7f 7e 65 8b
RSP: 0018:ffffc900001e0558 EFLAGS: 00000046
RAX: ffffffff818a8988 RBX: 0000000000000014 RCX: ffff88802f07d940
RDX: 0000000000000100 RSI: ffffc900001e05e0 RDI: 0000000000000014
RBP: ffffc900001e0668 R08: ffff8880b8f3580b R09: 1ffff110171e6b01
R10: dffffc0000000000 R11: ffffed10171e6b02 R12: ffffffff8cb7fc20
R13: ffffe8ffffd58090 R14: ffffc900001e05e0 R15: ffffc900001e0600
FS:  0000555572381500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5942fe7158 CR3: 0000000068639000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 perf_trace_buf_alloc+0x18/0x300 kernel/trace/trace_event_perf.c:403
 perf_trace_preemptirq_template+0x143/0x320 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 e2 33 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:ffffc900001e0760 EFLAGS: 00000206
RAX: 8a067ea557d41d00 RBX: 1ffff9200003c0f4 RCX: 8a067ea557d41d00
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0f60
RBP: ffffc900001e0860 R08: ffffffff90af6347 R09: 1ffffffff215ec68
R10: dffffc0000000000 R11: fffffbfff215ec69 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8f3b900 R15: 0000000000000002
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 ndisc_send_skb+0xd9d/0x14e0 net/ipv6/ndisc.c:521
 addrconf_rs_timer+0x2d1/0x630 net/ipv6/addrconf.c:3979
 call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x53e/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x2a1/0x930 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:kasan_quarantine_put+0x84/0x220 mm/kasan/quarantine.c:245
Code: e8 a1 75 b5 ff 48 c7 04 24 00 00 00 00 9c 8f 04 24 f7 04 24 00 02 00 00 0f 85 83 00 00 00 41 f7 c7 00 02 00 00 74 01 fb 31 c0 <48> 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f c3 48 8d 80 00 67 03 00 45
RSP: 0018:ffffc90003f778a8 EFLAGS: 00000206
RAX: 8a067ea557d41d01 RBX: ffff888028a6bf90 RCX: 8a067ea557d41d00
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0f60
RBP: ffff888028a6bf78 R08: ffffffff90af62c7 R09: 1ffffffff215ec58
R10: dffffc0000000000 R11: fffffbfff215ec59 R12: 0000000000000000
R13: ffffc90003f77940 R14: 00000000000cbc08 R15: 0000000000000286
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 __vunmap+0x942/0xa00 mm/vmalloc.c:2732
 copy_entries_to_user net/ipv4/netfilter/ip_tables.c:868 [inline]
 get_entries net/ipv4/netfilter/ip_tables.c:1024 [inline]
 do_ipt_get_ctl+0xead/0x1190 net/ipv4/netfilter/ip_tables.c:1670
 nf_getsockopt+0x25e/0x280 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x19b/0x230 net/ipv4/ip_sockglue.c:1826
 __sys_getsockopt+0x1b0/0x230 net/socket.c:2331
 __do_sys_getsockopt net/socket.c:2346 [inline]
 __se_sys_getsockopt net/socket.c:2343 [inline]
 __x64_sys_getsockopt+0xb1/0xc0 net/socket.c:2343
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f5942d9df6a
Code: 48 83 ec 10 89 d2 48 63 ff 45 31 c9 6a 2a 45 31 c0 31 c9 e8 d8 99 fb ff 48 83 c4 18 c3 0f 1f 00 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 06 c3 0f 1f 44 00 00 48 c7 c2 e8 ff ff ff f7
RSP: 002b:00007ffcfedf7e78 EFLAGS: 00000216 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007ffcfedf7f00 RCX: 00007f5942d9df6a
RDX: 0000000000000041 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007ffcfedf7e9c R09: 0000000000000000
R10: 00007ffcfedf7f00 R11: 0000000000000216 R12: 00007f5942fe9fc0
R13: 00007ffcfedf7e9c R14: 0000000000000000 R15: 00007f5942fec180
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/20 11:42 linux-6.1.y f2ddafa93a25 2f245add .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sys_getsockopt
2026/01/30 10:47 linux-6.1.y cd9b81672742 bfa73b7b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sys_getsockopt
2025/04/27 15:03 linux-6.1.y 535ec20c5027 c6b4fb39 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: rcu detected stall in sys_getsockopt
2025/10/06 20:37 linux-6.1.y 882efbdd9d34 91305dbe .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_getsockopt
2025/03/21 07:26 linux-6.1.y 344a09659766 62330552 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_getsockopt
* Struck through repros no longer work on HEAD.