INFO: rcu detected stall in sys_symlinkat (3)

Status: upstream: reported syz repro on 2025/05/03 06:00
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+9bdb9cb224274592f48b@syzkaller.appspotmail.com
First crash: 545d, last: 139d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/05/23 upstream (ToT) 94305e83eccb syz [report] INFO: rcu detected stall in corrupted
2026/08/29 upstream (ToT) cf72cbb39da8 syz Failed due to an error; will retry later
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_symlinkat (3) ext4 1 3 1190d 1242d 0/29 auto-obsoleted due to no activity on 2023/10/26 22:46
linux-5.15 INFO: rcu detected stall in sys_symlinkat 1 1 1253d 1253d 0/3 auto-obsoleted due to no activity on 2023/09/03 15:54
linux-5.15 INFO: rcu detected stall in sys_symlinkat (5) 1 1 49d 49d 0/3 upstream: reported on 2026/09/11 05:55
linux-5.15 INFO: rcu detected stall in sys_symlinkat (3) 1 2 865d 890d 0/3 auto-obsoleted due to no activity on 2024/09/25 17:37
upstream INFO: rcu detected stall in sys_symlinkat (5) prio:normal tomoyo mm 1 syz error error 152 2d06h 695d 0/29 upstream: reported syz repro on 2024/12/04 02:45
linux-6.1 INFO: rcu detected stall in sys_symlinkat (2) 1 1 1037d 1037d 0/3 auto-obsoleted due to no activity on 2024/04/06 00:16
upstream INFO: rcu detected stall in sys_symlinkat kvm 1 5 1522d 1622d 0/29 auto-obsoleted due to no activity on 2022/11/28 07:06
linux-6.1 INFO: rcu detected stall in sys_symlinkat 1 1 1282d 1282d 0/3 auto-obsoleted due to no activity on 2023/08/23 09:07
upstream INFO: rcu detected stall in sys_symlinkat (2) ext4 lsm 1 2 1335d 1429d 0/29 auto-obsoleted due to no activity on 2023/06/03 10:14
linux-6.6 INFO: rcu detected stall in sys_symlinkat (2) 1 1 36d 36d 0/2 upstream: reported on 2026/09/24 02:58
upstream INFO: task hung in addrconf_verify_work (9) net 1 syz 2352 24d 797d 0/29 closed as invalid on 2026/10/06 01:41
upstream INFO: rcu detected stall in sys_symlinkat (4) ext4 1 1 1066d 1066d 0/29 auto-obsoleted due to no activity on 2024/02/27 04:07
linux-5.15 INFO: rcu detected stall in sys_symlinkat (4) 1 2 281d 303d 0/3 auto-obsoleted due to no activity on 2026/05/02 14:14
linux-6.6 INFO: rcu detected stall in sys_symlinkat 1 1 244d 244d 0/2 auto-obsoleted due to no activity on 2026/06/08 11:28
linux-5.15 INFO: rcu detected stall in sys_symlinkat (2) 1 1 1062d 1062d 0/3 auto-obsoleted due to no activity on 2024/03/12 11:22
android-5-15 BUG: soft lockup in sys_symlinkat 1 13 837d 928d 0/2 auto-obsoleted due to no activity on 2024/10/13 01:26
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/01/22 08:34 7m bisect fix linux-6.1.y error job log
2025/08/14 06:14 2h29m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 1-.... } 2640 jiffies s: 4289 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: 4599 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:29 [inline]
RIP: 0010:rcu_dynticks_curr_cpu_in_eqs include/linux/context_tracking.h:122 [inline]
RIP: 0010:rcu_is_watching+0x56/0xa0 kernel/rcu/tree.c:721
Code: f0 48 c1 e8 03 42 80 3c 38 00 74 08 4c 89 f7 e8 70 f2 65 00 48 c7 c3 c8 57 03 00 49 03 1e 48 89 d8 48 c1 e8 03 42 0f b6 04 38 <84> c0 75 2f 8b 03 65 ff 0d 75 50 97 7e 74 0c 83 e0 04 c1 e8 02 5b
RSP: 0018:ffffc900001e07c0 EFLAGS: 00000806
RAX: 0000000000000000 RBX: ffff8880b8f357c8 RCX: 2bfd5f6441905a00
RDX: 0000000000000000 RSI: ffffffff8abef900 RDI: ffffffff8abef8c0
RBP: ffffc900001e08e8 R08: dffffc0000000000 R09: fffffbfff1bfe1c6
R10: fffffbfff1bfe1c6 R11: 1ffffffff1bfe1c5 R12: 0000000000000001
R13: 1ffff9200003c108 R14: ffffffff8c3d8988 R15: dffffc0000000000
FS:  0000555579a81500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe9b3851762 CR3: 0000000018a5b000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 trace_lock_acquire include/trace/events/lock.h:24 [inline]
 lock_acquire+0xe8/0x490 kernel/locking/lockdep.c:5633
 rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 rcu_read_lock include/linux/rcupdate.h:791 [inline]
 trace_call_bpf+0xe0/0x680 kernel/trace/bpf_trace.c:134
 perf_trace_run_bpf_submit+0x79/0x1c0 kernel/events/core.c:9997
 perf_trace_preemptirq_template+0x287/0x330 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+0x84/0x500 kernel/rcu/tree_plugin.h:685
Code: f1 f1 f1 00 f2 f2 f2 4a 89 04 2b 66 42 c7 44 2b 09 f3 f3 42 c6 44 2b 0b f3 65 44 8b 35 fd 86 96 7e 41 f7 c6 00 00 f0 00 74 45 <48> c7 44 24 40 0e 36 e0 45 4a c7 04 2b 00 00 00 00 66 42 c7 44 2b
RSP: 0018:ffffc900001e0c20 EFLAGS: 00000206
RAX: 2bfd5f6441905a00 RBX: 1ffff9200003c18c RCX: 2bfd5f6441905a00
RDX: dffffc0000000000 RSI: ffffffff8a6c0600 RDI: ffffffff8abef920
RBP: ffffc900001e0d08 R08: dffffc0000000000 R09: fffffbfff211905d
R10: fffffbfff211905d R11: 1ffffffff211905c 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]
 rebalance_domains+0x89c/0x9d0 kernel/sched/fair.c:11044
 handle_softirqs+0x2a1/0x920 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x12f/0x220 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_check_range+0x1ab/0x290 mm/kasan/generic.c:-1
Code: 4d 89 d6 4d 8d 56 07 4d 85 f6 4d 0f 49 d6 49 83 e2 f8 4d 29 d6 74 12 41 80 39 00 0f 85 a0 00 00 00 49 ff c1 49 ff ce 75 ee 5b <41> 5e 41 5f c3 84 db 75 61 f7 c3 00 ff 00 00 75 5e f7 c3 00 00 ff
RSP: 0018:ffffc900043b7d10 EFLAGS: 00000256
RAX: 0000000000000001 RBX: ffff88807895a7a8 RCX: ffffffff81644959
RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff88807895a7a8
RBP: ffff88807895a720 R08: dffffc0000000000 R09: ffffed100f12b4f6
R10: ffffed100f12b4f6 R11: 1ffff1100f12b4f5 R12: dffffc0000000000
R13: 0000000069385f9c R14: 0000000000000001 R15: dffffc0000000001
 instrument_atomic_read include/linux/instrumented.h:72 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 queued_spin_is_locked include/asm-generic/qspinlock.h:57 [inline]
 debug_spin_unlock kernel/locking/spinlock_debug.c:100 [inline]
 do_raw_spin_unlock+0x49/0x230 kernel/locking/spinlock_debug.c:140
 __raw_spin_unlock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_unlock+0x1a/0x40 kernel/locking/spinlock.c:186
 shmem_symlink+0x4e6/0x670 mm/shmem.c:3188
 vfs_symlink+0x247/0x3d0 fs/namei.c:4479
 do_symlinkat+0x1ae/0x3f0 fs/namei.c:4508
 __do_sys_symlinkat fs/namei.c:4525 [inline]
 __se_sys_symlinkat fs/namei.c:4522 [inline]
 __x64_sys_symlinkat+0x95/0xa0 fs/namei.c:4522
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe9b378ecc7
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 0a 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdfc0af038 EFLAGS: 00000202 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe9b378ecc7
RDX: 00007fe9b38158d7 RSI: 00000000ffffff9c RDI: 00007ffdfc0af0d0
RBP: 00007ffdfc0af07c R08: 0000000000000013 R09: 00007ffdfc0aed87
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000e
R13: 00000000000927c0 R14: 000000000001d146 R15: 00007ffdfc0af0d0
 </TASK>

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/09 17:43 linux-6.1.y 50cbba13faa2 d6526ea3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-perf INFO: rcu detected stall in sys_symlinkat
2025/05/03 16:57 linux-6.1.y b6736e03756f b0714e37 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_symlinkat
2026/06/13 03:00 linux-6.1.y 228da13e907e 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_symlinkat
2025/10/19 06:29 linux-6.1.y c2fda4b3f577 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_symlinkat
2025/05/03 05:59 linux-6.1.y b6736e03756f b0714e37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: rcu detected stall in sys_symlinkat
* Struck through repros no longer work on HEAD.