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: 339d, last: 5d11h
▶ ▼ 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 515d 515d 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 665d 665d 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 1315d 1400d 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 418 22h00m 1112d 0/29 upstream: reported C repro on 2023/08/13 23:42
linux-6.1 INFO: rcu detected stall in sys_unlink (2) 1 32 12d 521d 0/3 upstream: reported on 2025/03/27 11:38
linux-6.1 INFO: rcu detected stall in sys_unlink 1 4 731d 950d 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 784d 795d 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 47 12d 405d 0/2 upstream: reported on 2025/07/20 18:19
upstream INFO: rcu detected stall in sys_unlink mm kasan 1 1 1491d 1491d 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 901d 901d 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 843d 865d 0/2 auto-obsoleted due to no activity on 2024/08/07 01:29

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4188/1:b..l
	(detected by 0, t=10502 jiffies, g=32885, q=28)
task:syz-executor    state:R  running task     stack:21904 pid: 4188 ppid:  4185 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:xas_find+0x29f/0xa50 lib/xarray.c:1253
Code: 89 ec 49 c1 ec 03 43 0f b6 04 3c 84 c0 0f 85 8b 07 00 00 44 0f b6 75 00 45 89 ef 41 83 e7 3f 4c 89 ff 4c 89 f6 e8 21 34 6b fd <4d> 39 f7 0f 85 92 00 00 00 e8 33 32 6b fd 49 89 dc 49 bf 00 00 00
RSP: 0000:ffffc90002eff7a8 EFLAGS: 00000293
RAX: ffffffff840dcd5f RBX: ffffc90002eff8b8 RCX: ffff888073968000
RDX: 0000000000000000 RSI: 000000000000002b RDI: 000000000000002b
RBP: ffffc90002eff8b2 R08: ffff888073968000 R09: 0000000000000002
R10: 0000000000000003 R11: 0000000000000000 R12: 1ffff920005dff16
R13: 00000000000022ab R14: 000000000000002b R15: 000000000000002b
 find_get_entry mm/filemap.c:1978 [inline]
 find_lock_entries+0x19e/0xd70 mm/filemap.c:2092
 shmem_undo_range+0x292/0x19a0 mm/shmem.c:943
 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: 0033:0x7fcbc78cf1c7
RSP: 002b:00007fff5a9c6408 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fcbc78cf1c7
RDX: 00007fff5a9c6430 RSI: 00007fff5a9c64c0 RDI: 00007fff5a9c64c0
RBP: 00007fff5a9c64c0 R08: 00007fff5a9c74c0 R09: 00000000ffffffff
R10: 0000000000000100 R11: 0000000000000206 R12: 00007fff5a9c7550
R13: 00007fcbc7966474 R14: 0000000000056742 R15: 00007fff5a9c7590
 </TASK>
rcu: rcu_preempt kthread starved for 10502 jiffies! g32885 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:26896 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: 7771 Comm: syz.6.766 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 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+0x4d/0xc0 arch/x86/kernel/apic/apic.c:1108
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0033:0x7f68be243e57
Code: 8d 3d c0 9e 0b 00 e8 58 1d fa ff e8 a3 87 00 00 0f 1f 00 b8 68 00 00 00 0f 05 c3 0f 1f 84 00 00 00 00 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 b8 6e 00 00 00 0f 05 c3 0f 1f 84 00 00
RSP: 002b:00007f68bc480a48 EFLAGS: 00000206
RAX: 00000000000000cb RBX: 00007f68bc480bb0 RCX: 00007f68be243e57
RDX: 00007f68bc480a80 RSI: 00007f68bc480bb0 RDI: 0000000000000021
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000020000023896 R11: 0000000000000206 R12: 0000000000000000
R13: 00007f68be4d2128 R14: 00007f68be4d2090 R15: 00007ffee7502948
 </TASK>

Crashes (15):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.