syzbot

 sign-in | mailing list | source | docs
🐞 Open [825]
🐞 Fixed [84]
🐞 Invalid [1041]
⬇ Missing Backports [127]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in sys_umount

Status: auto-obsoleted due to no activity on 2024/09/25 03:07
Reported-by: syzbot+3231f4f155ae5f049559@syzkaller.appspotmail.com
First crash: 482d, last: 482d
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_umount (2) fs 1 1 1301d 1301d 0/29 auto-closed as invalid on 2022/06/20 00:56
linux-6.1 INFO: rcu detected stall in sys_umount origin:lts-only 1 C inconclusive 1 140d 140d 0/3 upstream: reported C repro on 2025/05/25 02:36
linux-5.15 INFO: rcu detected stall in sys_umount (2) 1 1 171d 171d 0/3 auto-obsoleted due to no activity on 2025/08/02 13:13
upstream INFO: rcu detected stall in sys_umount (3) mm 1 C done 44 8d10h 308d 0/29 upstream: reported C repro on 2024/12/08 08:40
upstream INFO: rcu detected stall in sys_umount mm 1 8 2272d 2276d 0/29 auto-closed as invalid on 2019/10/25 14:21
linux-6.6 INFO: rcu detected stall in sys_umount 1 1 73d 73d 0/2 upstream: reported on 2025/07/31 23:39

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P11077/1:b..l P3985/1:b..l P9071/1:b..l
	(detected by 1, t=10503 jiffies, g=53221, q=50)
task:syz-executor.0  state:R  running task     stack:20288 pid: 9071 ppid:  9062 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6780
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__sanitizer_cov_trace_pc+0x58/0x60 kernel/kcov.c:207
Code: 10 16 00 00 83 fa 02 75 21 48 8b 91 18 16 00 00 48 8b 32 48 8d 7e 01 8b 89 14 16 00 00 48 39 cf 73 08 48 89 44 f2 08 48 89 3a <c3> 0f 1f 80 00 00 00 00 4c 8b 04 24 65 48 8b 15 84 14 82 7e 65 8b
RSP: 0018:ffffc90003317a60 EFLAGS: 00000293
RAX: ffffffff83c346ed RBX: ffffffff8c362a08 RCX: ffff888077eb8000
RDX: 0000000000000000 RSI: 0000000000000081 RDI: ffff8880540f5260
RBP: 0000000000000000 R08: ffffffff83c34691 R09: fffff52000662f9a
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff8880540f5260
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000081
 security_inode_permission+0xad/0xf0 security/security.c:1328
 may_lookup fs/namei.c:1689 [inline]
 link_path_walk+0x270/0xd90 fs/namei.c:2245
 path_lookupat+0xa9/0x450 fs/namei.c:2454
 filename_lookup+0x230/0x5c0 fs/namei.c:2484
 user_path_at_empty+0x40/0x180 fs/namei.c:2883
 user_path_at include/linux/namei.h:57 [inline]
 ksys_umount fs/namespace.c:1779 [inline]
 __do_sys_umount fs/namespace.c:1787 [inline]
 __se_sys_umount fs/namespace.c:1785 [inline]
 __x64_sys_umount+0xf0/0x170 fs/namespace.c:1785
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f39fa4041d7
RSP: 002b:00007ffe1cc3e9f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f39fa4041d7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffe1cc3eab0
RBP: 00007ffe1cc3eab0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffe1cc3fb60
R13: 00007f39fa45f636 R14: 000000000007b487 R15: 0000000000000000
 </TASK>
task:kworker/u4:6    state:R  running task     stack:22168 pid: 3985 ppid:     2 flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_notrace+0xf8/0x140 kernel/sched/core.c:6631
 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:35
 rcu_is_watching+0x72/0xa0 kernel/rcu/tree.c:1124
 rcu_read_unlock include/linux/rcupdate.h:768 [inline]
 batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:772 [inline]
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:826 [inline]
 batadv_iv_ogm_schedule+0x652/0x1000 net/batman-adv/bat_iv_ogm.c:869
 batadv_iv_send_outstanding_bat_ogm_packet+0x6fa/0x800 net/batman-adv/bat_iv_ogm.c:1713
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
 </TASK>
task:syz-executor.2  state:R  running task     stack:25016 pid:11077 ppid: 10013 flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 preempt_schedule_common+0x83/0xd0 kernel/sched/core.c:6552
 preempt_schedule+0xd9/0xe0 kernel/sched/core.c:6577
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:34
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:202
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 loop_queue_work drivers/block/loop.c:1068 [inline]
 loop_queue_rq+0x9f7/0xae0 drivers/block/loop.c:2201
 __blk_mq_issue_directly block/blk-mq.c:2008 [inline]
 __blk_mq_try_issue_directly+0x541/0x8b0 block/blk-mq.c:2064
 blk_mq_try_issue_directly+0x116/0x370 block/blk-mq.c:2095
 blk_mq_submit_bio+0x11bb/0x1c40 block/blk-mq.c:2317
 __submit_bio+0x813/0x850 block/blk-core.c:917
 __submit_bio_noacct_mq block/blk-core.c:997 [inline]
 submit_bio_noacct+0x955/0xb30 block/blk-core.c:1027
 submit_bio+0x2dd/0x560 block/blk-core.c:1089
 submit_bh fs/buffer.c:3062 [inline]
 __sync_dirty_buffer+0x245/0x380 fs/buffer.c:3157
 ext4_commit_super+0x323/0x430 fs/ext4/super.c:5520
 ext4_remount+0x1e76/0x2f70 fs/ext4/super.c:5987
 reconfigure_super+0x43a/0x870 fs/super.c:925
 vfs_fsconfig_locked fs/fsopen.c:254 [inline]
 __do_sys_fsconfig fs/fsopen.c:439 [inline]
 __se_sys_fsconfig+0x98b/0xec0 fs/fsopen.c:314
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f7985b30ea9
RSP: 002b:00007f79846aa0c8 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00007f7985c67f80 RCX: 00007f7985b30ea9
RDX: 0000000000000000 RSI: 0000000000000007 RDI: 0000000000000004
RBP: 00007f7985b9fff4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f7985c67f80 R15: 00007ffca1aa73c8
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10582 jiffies! g53221 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=37253
rcu: rcu_preempt kthread starved for 10585 jiffies! g53221 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:26168 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5030 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1f0 kernel/sched/core.c:6459
 schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x2bf/0x1080 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0xa4/0x360 kernel/rcu/tree.c:2145
 kthread+0x3f6/0x4f0 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:300
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 11087 Comm: syz-executor.3 Not tainted 5.15.161-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:166 [inline]
 rcu_check_gp_kthread_starvation+0x1d2/0x240 kernel/rcu/tree_stall.h:487
 print_other_cpu_stall+0x137a/0x14d0 kernel/rcu/tree_stall.h:592
 check_cpu_stall kernel/rcu/tree_stall.h:745 [inline]
 rcu_pending kernel/rcu/tree.c:3932 [inline]
 rcu_sched_clock_irq+0xa38/0x1150 kernel/rcu/tree.c:2619
 update_process_times+0x196/0x200 kernel/time/timer.c:1818
 tick_sched_handle kernel/time/tick-sched.c:254 [inline]
 tick_sched_timer+0x386/0x550 kernel/time/tick-sched.c:1473
 __run_hrtimer kernel/time/hrtimer.c:1686 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1750
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1812
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1085 [inline]
 __sysvec_apic_timer_interrupt+0x139/0x470 arch/x86/kernel/apic/apic.c:1102
 sysvec_apic_timer_interrupt+0x8c/0xb0 arch/x86/kernel/apic/apic.c:1096
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:638
RIP: 0010:__raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
RIP: 0010:_raw_spin_unlock_irq+0x25/0x40 kernel/locking/spinlock.c:202
Code: 21 80 f6 ff 90 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 be 11 3b f7 48 89 df e8 96 65 3c f7 e8 b1 1d 5f f7 fb bf 01 00 00 00 <e8> d6 ab 2f f7 65 8b 05 57 b2 da 75 85 c0 74 02 5b c3 e8 24 cf d8
RSP: 0018:ffffc90002df7a50 EFLAGS: 00000282
RAX: c3079d71ccd6fd00 RBX: ffff8880641cdc80 RCX: ffffffff913f0f03
RDX: dffffc0000000000 RSI: ffffffff8a8b2a00 RDI: 0000000000000001
RBP: ffffc90002df7b30 R08: ffffffff8186db40 R09: ffffed100c839b91
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff1100ef83c4e
R13: ffff888077c1d940 R14: 0000000100000000 R15: 1ffff1100ef83c4d
 spin_unlock_irq include/linux/spinlock.h:413 [inline]
 __set_current_blocked+0x2a5/0x2f0 kernel/signal.c:3077
 set_current_blocked kernel/signal.c:3061 [inline]
 signal_delivered kernel/signal.c:2925 [inline]
 signal_setup_done+0x397/0x5f0 kernel/signal.c:2936
 handle_signal arch/x86/kernel/signal.c:842 [inline]
 arch_do_signal_or_restart+0x14a1/0x1890 arch/x86/kernel/signal.c:869
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x97/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff4e2c12630
Code: 83 c0 16 83 e0 f7 74 12 50 48 8d 3d 5a 9b 04 00 e8 35 78 fa ff 0f 1f 44 00 00 c3 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 <83> ff 21 74 0b c3 66 2e 0f 1f 84 00 00 00 00 00 55 53 48 89 f3 48
RSP: 002b:00007ff4e1721bb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000000 RBX: 00007ff4e2d22128 RCX: 00007ff4e2beaea9
RDX: 00007ff4e1721bc0 RSI: 00007ff4e1721cf0 RDI: 0000000000000021
RBP: 00007ff4e2d22120 R08: 00007ff4e17226c0 R09: 00007ff4e17226c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff4e2d2212c
R13: 000000000000006e R14: 00007ffe9b5b07f0 R15: 00007ffe9b5b08d8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/17 03:07 linux-5.15.y 4878aadf2d15 f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_umount
* Struck through repros no longer work on HEAD.