INFO: rcu detected stall in sys_symlink (2)

Status: upstream: reported on 2026/05/15 06:02
Reported-by: syzbot+7d482db8e92c5ad91d9f@syzkaller.appspotmail.com
First crash: 87d, last: 87d
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_symlink (6) prio:high fs mm 1 syz, C error inconclusive 6 93d 287d 0/29 upstream: reported C repro on 2025/10/27 21:18
linux-6.1 INFO: rcu detected stall in sys_symlink origin:lts-only 1 syz, C inconclusive 2 183d 198d 0/3 upstream: reported C repro on 2026/01/24 22:49
linux-5.15 INFO: rcu detected stall in sys_symlink 1 1 232d 232d 0/3 auto-obsoleted due to no activity on 2026/03/31 12:04
upstream INFO: rcu detected stall in sys_symlink (3) mm 1 4 2406d 2406d 0/29 closed as invalid on 2020/01/09 08:13
upstream INFO: rcu detected stall in sys_symlink (2) cgroups mm 1 2 2407d 2407d 0/29 closed as invalid on 2020/01/08 05:23
linux-6.6 INFO: rcu detected stall in sys_symlink 1 1 407d 407d 0/2 auto-obsoleted due to no activity on 2025/10/07 08:06
upstream INFO: rcu detected stall in sys_symlink mm 1 17 2442d 2443d 0/29 closed as invalid on 2019/12/04 14:14
upstream INFO: rcu detected stall in sys_symlink (4) bpf 1 11 1670d 1774d 0/29 closed as invalid on 2022/02/08 09:50
upstream INFO: rcu detected stall in sys_symlink (5) mm fs 1 syz inconclusive done 6 619d 669d 0/29 closed as invalid on 2025/02/03 10:48

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4299/1:b..l P4182/1:b..l
	(detected by 0, t=10502 jiffies, g=8537, q=158)
task:udevd           state:R  running task     stack:25552 pid: 4182 ppid:  3560 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x4b/0x400 kernel/locking/lockdep.c:5591
Code: 30 48 89 4c 24 28 89 d3 89 74 24 1c 49 89 fc 65 48 8b 04 25 28 00 00 00 48 89 84 24 c0 00 00 00 49 bf 00 00 00 00 00 fc ff df <48> c7 44 24 60 b3 8a b5 41 48 c7 44 24 68 ff 46 bc 8b 48 c7 44 24
RSP: 0018:ffffc90002e6f980 EFLAGS: 00000282
RAX: 4fde07bc09458b00 RBX: 0000000000000000 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8c31eb20
RBP: ffffc90002e6fa98 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff520005cdf7e R12: ffffffff8c31eb20
R13: 0000000000000040 R14: ffffc90002e6fbe0 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 path_init+0x104/0x1160 fs/namei.c:2344
 path_parentat fs/namei.c:2509 [inline]
 __filename_parentat+0x247/0x690 fs/namei.c:2534
 filename_parentat fs/namei.c:2552 [inline]
 filename_create+0xd5/0x470 fs/namei.c:3824
 do_symlinkat+0xbc/0x6b0 fs/namei.c:4456
 __do_sys_symlink fs/namei.c:4488 [inline]
 __se_sys_symlink fs/namei.c:4486 [inline]
 __x64_sys_symlink+0x7a/0x90 fs/namei.c:4486
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fe11a511527
RSP: 002b:00007ffdbe86a528 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00005646eb850320 RCX: 00007fe11a511527
RDX: fffffffffffffe68 RSI: 00007ffdbe86a530 RDI: 00005646eb845e80
RBP: 00000000000000c5 R08: 0000000000000064 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007ffdbe86a530
R13: 00005646eb84e410 R14: 0000000000000008 R15: 00005646eb850320
 </TASK>
task:kworker/u4:9    state:R  running task     stack:26128 pid: 4299 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_nc_worker
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:27 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:172 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:227 [inline]
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0xc/0x80 kernel/kcov.c:293
Code: 44 02 08 03 00 00 00 4a 89 7c 02 10 4a 89 74 02 18 4a 89 44 02 20 48 ff c1 48 89 0a c3 90 48 8b 04 24 65 48 8b 0d c4 37 89 7e <65> 8b 15 c5 37 89 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75
RSP: 0018:ffffc9000363fbd8 EFLAGS: 00000246
RAX: ffffffff89915113 RBX: dffffc0000000000 RCX: ffff88802ab13b80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: 1ffffffff203aa18
R10: dffffc0000000000 R11: fffffbfff203aa19 R12: 000000000000020e
R13: fffffffffffffe38 R14: ffff888029630c80 R15: ffff88805f3484d0
 rcu_read_unlock include/linux/rcupdate.h:769 [inline]
 batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline]
 batadv_nc_worker+0x1d3/0x5c0 net/batman-adv/network-coding.c:723
 process_one_work+0x85f/0x1010 kernel/workqueue.c:2310
 worker_thread+0xaa6/0x1290 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: rcu_preempt kthread starved for 10553 jiffies! g8537 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27536 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11ef/0x43c0 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x184/0x2d0 kernel/time/timer.c:2117
 rcu_gp_fqs_loop+0x2be/0x11d0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9b/0x370 kernel/rcu/tree.c:2145
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4572 Comm: syz.0.73 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:bytes_is_nonzero mm/kasan/generic.c:87 [inline]
RIP: 0010:memory_is_nonzero mm/kasan/generic.c:102 [inline]
RIP: 0010:memory_is_poisoned_n mm/kasan/generic.c:128 [inline]
RIP: 0010:memory_is_poisoned mm/kasan/generic.c:159 [inline]
RIP: 0010:check_region_inline mm/kasan/generic.c:180 [inline]
RIP: 0010:kasan_check_range+0x8a/0x290 mm/kasan/generic.c:189
Code: 1c 21 49 89 df 4d 29 df 49 83 ff 10 7f 29 4d 85 ff 0f 84 38 01 00 00 4c 89 cb 48 f7 d3 4c 01 f3 41 80 3b 00 0f 85 86 01 00 00 <49> ff c3 48 ff c3 75 ee e9 18 01 00 00 44 89 dd 83 e5 07 0f 84 b5
RSP: 0018:ffffc9000369f770 EFLAGS: 00000046
RAX: 0000000000000001 RBX: ffffffffffffffff RCX: ffffffff815d23b3
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff901d50d0
RBP: ffffc9000369f9f0 R08: ffffffff901d50d7 R09: 1ffffffff203aa1a
R10: dffffc0000000000 R11: fffffbfff203aa1a R12: dffffc0000000001
R13: ffff888022578000 R14: 1ffffffff203aa1a R15: 0000000000000001
FS:  000055557a67e500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f35c85f1ff8 CR3: 000000007d130000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 <TASK>
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:134 [inline]
 __lock_acquire+0xdc3/0x7d10 kernel/locking/lockdep.c:4982
 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
 _raw_spin_lock_irq+0xab/0xf0 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:389 [inline]
 get_signal+0x255/0x12c0 kernel/signal.c:2697
 arch_do_signal_or_restart+0xe7/0x12c0 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f35ca28e6e9
Code: 90 49 8b 4f 40 c6 04 01 00 48 83 c0 01 48 39 f0 72 ef e9 89 fe ff ff 66 2e 0f 1f 84 00 00 00 00 00 48 8b 0d 91 09 3a 00 31 c0 <48> 81 ce ff ff ff 3f 48 3b 34 c1 74 14 48 83 c0 01 48 83 f8 04 0f
RSP: 002b:00007ffc95293c50 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffffff81a2fbf8 RCX: 000000110c230000
RDX: 0000000000001bf8 RSI: ffffffff81a2fbf8 RDI: 0000000000000008
RBP: 0000000000000000 R08: 00007f35ca61d000 R09: 00007f35ca61f000
R10: 0000000081a2fbfc R11: 0000000000000008 R12: 00007f35ca633128
R13: 0000000000000617 R14: ffffffff81a2fe73 R15: 00007f35cb162720
 </TASK>
sched: RT throttling activated

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/15 06:02 linux-5.15.y de8dfb3f0278 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_symlink
* Struck through repros no longer work on HEAD.