INFO: rcu detected stall in sys_utimensat

Status: upstream: reported C repro on 2025/07/19 08:31
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+a139b1a93fe7c028962c@syzkaller.appspotmail.com
First crash: 389d, last: 58d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/07/20 linux-5.15.y (ToT) c79648372d02 C [report] INFO: rcu detected stall in corrupted
2025/07/20 upstream (ToT) f4a40a4282f4 C Didn't crash
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_utimensat (3) usb 1 syz, C 9 660d 680d 0/29 auto-obsoleted due to no activity on 2025/01/29 23:25
upstream INFO: rcu detected stall in sys_utimensat mm 1 1 2445d 2445d 0/29 closed as invalid on 2019/12/04 14:14
upstream INFO: rcu detected stall in sys_utimensat (2) fs 1 1 1706d 1706d 0/29 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_utimensat (5) prio:high fs 1 1 99d 99d 0/29 auto-obsoleted due to no activity on 2026/08/03 21:46
upstream INFO: rcu detected stall in sys_utimensat (4) fs 1 5 228d 264d 0/29 auto-obsoleted due to no activity on 2026/03/27 23:33
▶ ▼ Last patch testing requests (4)
Created Duration User Patch Repo Result
2026/07/04 02:05 21m retest repro linux-5.15.y report log
2026/04/06 12:49 36m retest repro linux-5.15.y report log
2026/01/26 06:11 18m retest repro linux-5.15.y report log
2025/11/16 17:46 13m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (7)
Created Duration User Patch Repo Result
2026/06/15 10:52 14m fix candidate upstream error job log
2026/05/10 23:08 13m fix candidate upstream error job log
2026/03/28 08:33 1m fix candidate upstream error job log
2026/02/25 03:29 3m fix candidate upstream error job log
2026/01/24 14:08 1m fix candidate upstream error job log
2025/11/22 18:32 27m fix candidate upstream error job log
2025/09/04 23:14 3m bisect fix linux-5.15.y error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P3658/1:b..l P4091/1:b..l
	(detected by 0, t=10502 jiffies, g=5937, q=162)
task:udevd           state:R  running task     stack:    0 pid: 4091 ppid:  3658 flags:0x00000004
Call trace:
 __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0xe00/0x1c0c kernel/sched/core.c:6376
 preempt_schedule_irq+0x90/0x214 kernel/sched/core.c:6780
 arm64_preempt_schedule_irq+0x14c/0x21c arch/arm64/kernel/entry-common.c:260
 el1_interrupt+0x40/0x58 arch/arm64/kernel/entry-common.c:463
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470
 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522
 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline]
 seqcount_lockdep_reader_access+0x214/0x2bc include/linux/seqlock.h:105
 __follow_mount_rcu fs/namei.c:1457 [inline]
 handle_mounts fs/namei.c:1490 [inline]
 step_into+0x4cc/0xa24 fs/namei.c:1806
 walk_component+0x1f0/0x3a8 fs/namei.c:1982
 link_path_walk+0x590/0xb8c fs/namei.c:-1
 path_lookupat+0x90/0x3d0 fs/namei.c:2454
 filename_lookup+0x180/0x414 fs/namei.c:2484
 user_path_at_empty+0x5c/0x1a0 fs/namei.c:2883
 user_path_at include/linux/namei.h:57 [inline]
 do_utimes_path fs/utimes.c:94 [inline]
 do_utimes+0x130/0x288 fs/utimes.c:144
 __do_sys_utimensat fs/utimes.c:163 [inline]
 __se_sys_utimensat fs/utimes.c:147 [inline]
 __arm64_sys_utimensat+0x144/0x210 fs/utimes.c:147
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
task:udevd           state:R  running task     stack:    0 pid: 3658 ppid:     1 flags:0x00000004
Call trace:
 __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0xe00/0x1c0c kernel/sched/core.c:6376
 preempt_schedule_common+0x138/0x218 kernel/sched/core.c:6552
 preempt_schedule+0x64/0x84 kernel/sched/core.c:6577
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
 _raw_spin_unlock_irqrestore+0x108/0x14c kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:418 [inline]
 __wake_up_common_lock kernel/sched/wait.c:140 [inline]
 __wake_up_sync_key+0x11c/0x178 kernel/sched/wait.c:205
 sock_def_readable+0x150/0x278 net/core/sock.c:3093
 __netlink_sendskb net/netlink/af_netlink.c:1264 [inline]
 netlink_sendskb+0xa4/0x178 net/netlink/af_netlink.c:1270
 netlink_unicast+0x2d8/0x8b0 net/netlink/af_netlink.c:1359
 netlink_sendmsg+0x6e8/0x9cc net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:704 [inline]
 __sock_sendmsg net/socket.c:716 [inline]
 ____sys_sendmsg+0x61c/0x920 net/socket.c:2436
 ___sys_sendmsg+0x1d0/0x240 net/socket.c:2490
 __sys_sendmsg net/socket.c:2519 [inline]
 __do_sys_sendmsg net/socket.c:2528 [inline]
 __se_sys_sendmsg net/socket.c:2526 [inline]
 __arm64_sys_sendmsg+0x1a8/0x254 net/socket.c:2526
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
rcu: rcu_preempt kthread starved for 10506 jiffies! g5937 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:    0 pid:   15 ppid:     2 flags:0x00000008
Call trace:
 __switch_to+0x2f4/0x558 arch/arm64/kernel/process.c:521
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0xe00/0x1c0c kernel/sched/core.c:6376
 schedule+0x11c/0x1c8 kernel/sched/core.c:6459
 schedule_timeout+0x180/0x2c8 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x25c/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xc4/0x2a8 kernel/rcu/tree.c:2145
 kthread+0x374/0x454 kernel/kthread.c:334
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:855
rcu: Stack dump where RCU GP kthread last ran:
Task dump for CPU 0:
task:syz.0.16        state:R  running task     stack:    0 pid: 4237 ppid:  4171 flags:0x00000001
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 sched_show_task+0x3c8/0x4b4 kernel/sched/core.c:8640
 dump_cpu_task+0x84/0xa8 kernel/sched/core.c:10927
 rcu_check_gp_kthread_starvation+0x1e8/0x274 kernel/rcu/tree_stall.h:488
 print_other_cpu_stall+0x1a24/0x1c10 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3936 [inline]
 rcu_sched_clock_irq+0x1558/0x1810 kernel/rcu/tree.c:2619
 update_process_times+0x1c4/0x260 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x30c/0x4bc kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1690 [inline]
 __hrtimer_run_queues+0x3fc/0xb6c kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x2bc/0xb5c kernel/time/hrtimer.c:1816
 timer_handler drivers/clocksource/arm_arch_timer.c:659 [inline]
 arch_timer_handler_virt+0x74/0x88 drivers/clocksource/arm_arch_timer.c:670
 handle_percpu_devid_irq+0x29c/0x76c kernel/irq/chip.c:930
 generic_handle_irq_desc include/linux/irqdesc.h:158 [inline]
 handle_irq_desc kernel/irq/irqdesc.c:652 [inline]
 handle_domain_irq+0x144/0x1fc kernel/irq/irqdesc.c:707
 gic_handle_irq+0x78/0x1c8 drivers/irqchip/irq-gic-v3.c:765
 call_on_irq_stack+0x24/0x30 arch/arm64/kernel/entry.S:855
 do_interrupt_handler+0x6c/0x88 arch/arm64/kernel/entry-common.c:267
 el1_interrupt+0x30/0x58 arch/arm64/kernel/entry-common.c:454
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:470
 el1h_64_irq+0x78/0x7c arch/arm64/kernel/entry.S:522
 arch_local_irq_restore+0x8/0x10 arch/arm64/include/asm/irqflags.h:122
 lock_is_held include/linux/lockdep.h:287 [inline]
 ___might_sleep+0x98/0x4d4 kernel/sched/core.c:9605
 __might_sleep+0x98/0x124 kernel/sched/core.c:9593
 __might_fault+0x80/0x128 mm/memory.c:5354
 setup_sigframe arch/arm64/kernel/signal.c:630 [inline]
 setup_rt_frame arch/arm64/kernel/signal.c:792 [inline]
 handle_signal arch/arm64/kernel/signal.c:833 [inline]
 do_signal arch/arm64/kernel/signal.c:908 [inline]
 do_notify_resume+0xcbc/0x3128 arch/arm64/kernel/signal.c:946
 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline]
 el0_svc+0xf0/0x1e0 arch/arm64/kernel/entry-common.c:609
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/19 08:31 linux-5.15.y c79648372d02 7117feec .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_utimensat
2026/06/15 06:52 linux-5.15.y dc027a595035 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_utimensat
2026/04/06 22:49 linux-5.15.y 91d48252ad4b 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_utimensat
2025/12/12 21:50 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_utimensat
2025/07/30 02:28 linux-5.15.y c79648372d02 f8f2b4da .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_utimensat
* Struck through repros no longer work on HEAD.