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: 317d, last: 2d18h
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 2217d 2217d 0/29 closed as invalid on 2020/01/08 05:23
linux-4.19 INFO: rcu detected stall in sys_getsockopt 1 1 1229d 1229d 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 763d 776d 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 782d 782d 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 434d 468d 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 2217d 2217d 0/29 closed as invalid on 2020/01/08 05:33
linux-6.6 INFO: rcu detected stall in sys_getsockopt (2) 1 1 72d 72d 0/2 upstream: reported on 2025/11/22 01:54
upstream INFO: rcu detected stall in sys_getsockopt (4) mm 1 3 2216d 2216d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_getsockopt (6) kvm 1 3 1634d 1702d 0/29 auto-closed as invalid on 2021/11/10 12:58
linux-6.6 INFO: rcu detected stall in sys_getsockopt 1 1 200d 200d 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 1491d 1541d 0/29 closed as invalid on 2022/02/08 10:10
upstream INFO: rcu detected stall in sys_getsockopt (5) sctp 1 2 2034d 2077d 0/29 auto-closed as invalid on 2020/10/06 19:28
linux-6.1 INFO: rcu detected stall in sys_getsockopt 1 4 699d 857d 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 894d 976d 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 221d 243d 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 1098d 1253d 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 1382d 1397d 0/29 auto-closed as invalid on 2022/07/21 00:25
upstream INFO: rcu detected stall in sys_getsockopt mm 1 2 2251d 2252d 0/29 closed as invalid on 2019/12/04 14:04
android-54 BUG: soft lockup in sys_getsockopt 1 1 656d 656d 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 551d 649d 0/2 auto-obsoleted due to no activity on 2024/10/28 21:41
Fix bisection attempts (4)
Created Duration User Patch Repo Result
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: { 0-.... } 2676 jiffies s: 3173 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: 4387 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:asm_sysvec_irq_work+0x0/0x20 arch/x86/include/asm/idtentry.h:722
Code: e9 b5 03 00 00 90 90 90 90 90 0f 01 ca fc 6a ff e8 b5 02 00 00 48 89 c4 48 89 e7 e8 ca 1f ec ff e9 95 03 00 00 90 90 90 90 90 <0f> 01 ca fc 6a ff e8 95 02 00 00 48 89 c4 48 89 e7 e8 9a 24 ec ff
RSP: 0018:ffffc90000007558 EFLAGS: 00000006
RAX: 58119ec49abcfc00 RBX: 1ffff92000000eb8 RCX: 58119ec49abcfc00
RDX: dffffc0000000000 RSI: ffffffff8a8c1220 RDI: ffffffff8adf0c20
RBP: ffffc90000007670 R08: ffffffff90af32c7 R09: 1ffffffff215e658
R10: dffffc0000000000 R11: fffffbfff215e659 R12: 0000000000000246
R13: dffffc0000000000 R14: ffff8880b8e3b900 R15: 0000000000000001
FS:  00005555725bd500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c0025a1000 CR3: 000000007e184000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
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 92 30 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:ffffc90000007580 EFLAGS: 00000206
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:823 [inline]
 is_bpf_text_address+0x27a/0x2a0 kernel/bpf/core.c:737
 kernel_text_address+0x9c/0xd0 kernel/extable.c:125
 __kernel_text_address+0x9/0x30 kernel/extable.c:79
 unwind_get_return_address+0x49/0x80 arch/x86/kernel/unwind_orc.c:323
 arch_stack_walk+0xf2/0x140 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xa6/0xf0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 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
 rcu_do_batch kernel/rcu/tree.c:2297 [inline]
 rcu_core+0xa99/0x1740 kernel/rcu/tree.c:2557
 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:filter_irq_stacks+0x2e/0x90 kernel/stacktrace.c:395
Code: 41 55 41 54 53 85 f6 74 70 49 89 fe 41 89 f4 31 db 49 bd 00 00 00 00 00 fc ff df 49 89 ff 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 <74> 08 4c 89 ff e8 38 2c 62 00 49 8b 04 de 48 3d e0 01 40 8a 0f 93
RSP: 0018:ffffc90003307668 EFLAGS: 00000246
RAX: 1ffff92000660ee4 RBX: 0000000000000004 RCX: 0000000000000801
RDX: 0000000000000001 RSI: 000000000000000c RDI: ffffc90003307700
RBP: ffffc90003307930 R08: 0000000000000001 R09: 1ffffffff1c3f865
R10: dffffc0000000000 R11: fffffbfff1c3f866 R12: 000000000000000c
R13: dffffc0000000000 R14: ffffc90003307700 R15: ffffc90003307720
 __stack_depot_save+0x35/0x460 lib/stackdepot.c:439
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_set_track+0x60/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 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
 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: 0033:0x7f49b6d9c6aa
Code: 48 83 ec 10 89 d2 48 63 ff 45 31 c9 6a 2a 45 31 c0 31 c9 e8 58 9a 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:00007ffcbce92cb8 EFLAGS: 00000216 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007ffcbce92d40 RCX: 00007f49b6d9c6aa
RDX: 0000000000000041 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007ffcbce92cdc R09: 0000000000000000
R10: 00007ffcbce92d40 R11: 0000000000000216 R12: 00007f49b6fe3960
R13: 00007ffcbce92cdc R14: 0000000000000000 R15: 00007f49b6fe4020
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.