INFO: rcu detected stall in sys_unlink (5)

Status: upstream: reported on 2025/09/25 16:42
Reported-by: syzbot+5854e0c59e957bb696cd@syzkaller.appspotmail.com
First crash: 354d, last: 10d
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: rcu detected stall in sys_unlink (4) 1 1 531d 531d 0/3 auto-obsoleted due to no activity on 2025/07/10 21:02
linux-5.15 INFO: rcu detected stall in sys_unlink (3) 1 1 681d 681d 0/3 auto-obsoleted due to no activity on 2025/02/11 14:08
upstream INFO: rcu detected stall in sys_unlink (2) kernel 1 2 1331d 1416d 0/29 auto-obsoleted due to no activity on 2023/04/22 20:06
upstream INFO: rcu detected stall in sys_unlink (3) mm 1 syz, C error 423 11d 1128d 0/29 upstream: reported C repro on 2023/08/13 23:42
linux-6.1 INFO: rcu detected stall in sys_unlink (2) 1 34 7d19h 537d 0/3 upstream: reported on 2025/03/27 11:38
linux-6.1 INFO: rcu detected stall in sys_unlink 1 4 747d 966d 0/3 auto-obsoleted due to no activity on 2024/12/07 03:28
linux-5.15 INFO: rcu detected stall in sys_unlink (2) 1 3 800d 811d 0/3 auto-obsoleted due to no activity on 2024/10/15 13:02
linux-6.6 INFO: rcu detected stall in sys_unlink 1 48 10d 421d 0/2 upstream: reported on 2025/07/20 18:19
upstream INFO: rcu detected stall in sys_unlink mm kasan 1 1 1507d 1507d 0/29 auto-obsoleted due to no activity on 2022/10/29 07:23
linux-5.15 INFO: rcu detected stall in sys_unlink 1 1 917d 917d 0/3 auto-obsoleted due to no activity on 2024/06/20 14:47
android-5-15 BUG: soft lockup in sys_unlink 1 7 859d 881d 0/2 auto-obsoleted due to no activity on 2024/08/07 01:29

Sample crash report:
usb 8-1: NFC: Urb failure (status -71)
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P6157/1:b..l
	(detected by 0, t=10502 jiffies, g=116861, q=75)
task:syz-executor    state:R  running task     stack:21904 pid: 6157 ppid:  6147 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 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+0x1d/0x400 kernel/locking/lockdep.c:5591
Code: 31 85 a5 7e a9 00 ff ff 00 0f 95 c0 c3 55 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 e4 e0 48 81 ec e0 00 00 00 4c 89 4c 24 20 <4c> 89 44 24 30 48 89 4c 24 28 89 d3 89 74 24 1c 49 89 fc 65 48 8b
RSP: 0018:ffffc9000337f660 EFLAGS: 00000286
RAX: 0000000000000001 RBX: ffff88807770c010 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8c31ef60
RBP: ffffc9000337f778 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff94000242e61 R12: dffffc0000000000
R13: ffff888019d84050 R14: ffffea0001217308 R15: ffffc9000337f7c8
 rcu_lock_acquire+0x20/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 percpu_ref_put_many include/linux/percpu-refcount.h:317 [inline]
 percpu_ref_put+0x16/0x150 include/linux/percpu-refcount.h:338
 __mem_cgroup_uncharge_list+0x6c/0xc0 mm/memcontrol.c:7004
 mem_cgroup_uncharge_list include/linux/memcontrol.h:720 [inline]
 release_pages+0x1857/0x1bd0 mm/swap.c:962
 __pagevec_release+0x6d/0xe0 mm/swap.c:983
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x5cd/0x19a0 mm/shmem.c:964
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x1e2/0x9a0 mm/shmem.c:1145
 evict+0x4b6/0x8b0 fs/inode.c:647
 do_unlinkat+0x3e7/0x710 fs/namei.c:4406
 __do_sys_unlink fs/namei.c:4447 [inline]
 __se_sys_unlink fs/namei.c:4445 [inline]
 __x64_sys_unlink+0x45/0x50 fs/namei.c:4445
 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: 0033:0x7f04bf7cc247
RSP: 002b:00007ffe09b3bcb8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f04bf7cc247
RDX: 00007ffe09b3bce0 RSI: 00007ffe09b3bd70 RDI: 00007ffe09b3bd70
RBP: 00007ffe09b3bd70 R08: 00007ffe09b3cd70 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffe09b3ce00
R13: 00007f04bf863474 R14: 0000000000161ac0 R15: 00007ffe09b3ce40
 </TASK>
rcu: rcu_preempt kthread starved for 10500 jiffies! g116861 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:27024 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 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/0x11f0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x9a/0x370 kernel/rcu/tree.c:2145
 kthread+0x42e/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:
NMI backtrace for cpu 0
CPU: 0 PID: 16755 Comm: syz.0.2804 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <IRQ>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1cd/0x250 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x1110/0x1270 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+0x845/0x1120 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:2021
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x37d/0x560 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1685 [inline]
 __hrtimer_run_queues+0x4b0/0xb60 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x397/0x8b0 kernel/time/hrtimer.c:1811
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x137/0x4a0 arch/x86/kernel/apic/apic.c:1114
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:lock_acquire+0x208/0x400 kernel/locking/lockdep.c:5627
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3d 04 f8 0f 85 f1 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 43 c7 44 3d 08 00 00 00 00 65 48 8b 04
RSP: 0018:ffffc90002ecf460 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000000 RCX: 30992c2eba688500
RDX: 0000000000000000 RSI: ffffffff8a2b3e80 RDI: ffffffff8a7a4540
RBP: ffffc90002ecf578 R08: dffffc0000000000 R09: 1ffffffff203de18
R10: dffffc0000000000 R11: fffffbfff203de19 R12: ffffffff8c31ef60
R13: 1ffff920005d9e98 R14: 0000000000000246 R15: dffffc0000000000
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 kstat_irqs_usr+0x1f/0x430 kernel/irq/irqdesc.c:979
 show_all_irqs fs/proc/stat.c:102 [inline]
 show_stat+0x165e/0x1970 fs/proc/stat.c:197
 seq_read_iter+0x460/0xc50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2173 [inline]
 generic_file_splice_read+0x3ed/0x5f0 fs/splice.c:311
 do_splice_to fs/splice.c:807 [inline]
 splice_direct_to_actor+0x41f/0xc00 fs/splice.c:881
 do_splice_direct+0x1d4/0x2f0 fs/splice.c:1008
 do_sendfile+0x524/0xe30 fs/read_write.c:1249
 __do_sys_sendfile64 fs/read_write.c:1317 [inline]
 __se_sys_sendfile64+0x141/0x1a0 fs/read_write.c:1303
 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: 0033:0x7f15f54d1159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f15f3708028 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f15f5759090 RCX: 00007f15f54d1159
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000005
RBP: 00007f15f5568024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f15f5759128 R14: 00007f15f5759090 R15: 00007ffd75e954f8
 </TASK>

Crashes (16):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/04 20:22 linux-5.15.y 0996e0926f6b f65209a4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/08/25 05:47 linux-5.15.y 945fa863f02c 614e416a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/08/21 23:00 linux-5.15.y 0eb903b5b519 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/08/17 16:50 linux-5.15.y aabd761612db 905244d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/08/11 22:34 linux-5.15.y aabd761612db 71790083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/07/19 06:07 linux-5.15.y c86c4726e7f0 72524a66 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/05/15 07:44 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_unlink
2026/05/15 07:35 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_unlink
2026/05/15 07:33 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_unlink
2026/04/27 13:34 linux-5.15.y b9d57c40a767 0f700595 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/02/14 01:09 linux-5.15.y e45d5d41c134 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/02/09 15:49 linux-5.15.y 7b232985052f df949cd9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2026/01/17 18:50 linux-5.15.y 68efe5a6c16a 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_unlink
2025/12/12 23:13 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_unlink
2025/12/09 06:00 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_unlink
2025/09/25 16:42 linux-5.15.y 43bb85222e53 0abd0691 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_unlink
* Struck through repros no longer work on HEAD.