syzbot

 sign-in | mailing list | source | docs
🐞 Open [852]
🐞 Fixed [87]
🐞 Invalid [1240]
⬇ Missing Backports [132]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in keyctl

Status: upstream: reported on 2025/12/05 22:03
Reported-by: syzbot+9b778e9baf45c4a7a4f0@syzkaller.appspotmail.com
First crash: 97d, last: 97d
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in keyctl (2) crypto 1 1 103d 103d 0/29 auto-obsoleted due to no activity on 2026/02/27 23:41
upstream INFO: rcu detected stall in keyctl bpf 1 1 224d 224d 0/29 auto-obsoleted due to no activity on 2025/10/30 04:37
upstream INFO: rcu detected stall in sys_keyctl (2) keyrings lsm 1 1 628d 628d 0/29 auto-obsoleted due to no activity on 2024/08/21 21:13
upstream INFO: rcu detected stall in sys_keyctl crypto 1 1 2200d 2199d 0/29 auto-closed as invalid on 2020/07/02 05:07
android-5-15 BUG: soft lockup in sys_keyctl 1 2 682d 683d 0/2 auto-obsoleted due to no activity on 2024/07/28 11:55

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	1-...!: (1 GPs behind) idle=6e5/1/0x4000000000000000 softirq=15108/15109 fqs=1 
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P144/1:b..l
	(detected by 0, t=10502 jiffies, g=19153, q=63)
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 6145 Comm: syz.5.379 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__lock_is_held kernel/locking/lockdep.c:5367 [inline]
RIP: 0010:lock_is_held_type+0xd4/0x190 kernel/locking/lockdep.c:5666
Code: 49 ff c4 48 63 83 e8 0a 00 00 49 83 c7 28 49 39 c4 7c d8 eb 11 48 c7 c7 80 bf fe 8b 4c 89 e6 e8 d2 56 51 fa eb cb 31 ed eb 20 <83> fd ff 74 16 89 e9 31 c0 41 f6 47 22 03 0f 95 c0 31 ed 39 c1 40
RSP: 0018:ffffc90000dd0cd8 EFLAGS: 00000002
RAX: 0000000000000001 RBX: ffff88807e059dc0 RCX: 0000000000000001
RDX: 0000000000010000 RSI: ffff8880b912a258 RDI: ffff88807e05a8d8
RBP: 00000000ffffffff R08: dffffc0000000000 R09: ffff88807b444b40
R10: ffffed100f68896b R11: 1ffff1100f688968 R12: 0000000000000001
R13: 0000000000000046 R14: ffff8880b912a258 R15: ffff88807e05a8d8
FS:  00007fb3dcf316c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c426a67 CR3: 000000001f69c000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_is_held include/linux/lockdep.h:287 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1651 [inline]
 __hrtimer_run_queues+0x2b0/0xc40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 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:key_lookup+0x98/0x2a0 security/keys/key.c:671
Code: 1d 06 48 8b 1d d9 78 90 12 48 85 db 0f 84 98 00 00 00 4c 8d 63 fc 4c 89 e0 48 c1 e8 03 42 0f b6 04 28 84 c0 75 66 45 8b 24 24 <44> 89 ff 44 89 e6 e8 5d 2f e2 fd 45 39 e7 7d 0c e8 f3 2d e2 fd b8
RSP: 0018:ffffc900042ffa00 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff8881447cce08 RCX: 0000000000080000
RDX: ffffc90016000000 RSI: 0000000000000059 RDI: 000000000000005a
RBP: ffffc900042ffa90 R08: 0000000000000004 R09: 0000000000000003
R10: fffff5200085ff30 R11: 1ffff9200085ff30 R12: 000000000c23dd28
R13: dffffc0000000000 R14: 1ffff9200085ff40 R15: 000000000fea3367
 lookup_user_key+0x947/0x10d0 security/keys/process_keys.c:749
 keyctl_keyring_search+0x14e/0x370 security/keys/keyctl.c:738
 __do_sys_keyctl security/keys/keyctl.c:1910 [inline]
 __se_sys_keyctl+0x4ba/0x960 security/keys/keyctl.c:1874
 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: 0033:0x7fb3decca749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fb3dcf31038 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa
RAX: ffffffffffffffda RBX: 00007fb3def20fa0 RCX: 00007fb3decca749
RDX: 0000200000000300 RSI: 000000000fea3367 RDI: 000000000000000a
RBP: 00007fb3ded4ef91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb3def21038 R14: 00007fb3def20fa0 R15: 00007ffc124745b8
 </TASK>
task:kworker/u4:1    state:R  running task     stack:23624 pid:  144 ppid:     2 flags:0x00004000
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 preempt_schedule_irq+0xb1/0x150 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:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:206
Code: a4 a3 8a 7e 65 8b 15 a5 a3 8a 7e 81 e2 00 01 ff 00 74 11 81 fa 00 01 00 00 75 35 83 b9 34 16 00 00 00 74 2c 8b 91 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
RSP: 0018:ffffc9000164fa38 EFLAGS: 00000246
RAX: ffffffff885529d7 RBX: 0000000000000001 RCX: ffff88801b655940
RDX: 0000000000000000 RSI: ffffffff8a59e560 RDI: ffffffff8a59e520
RBP: ffffc9000164fb50 R08: dffffc0000000000 R09: fffffbfff1ff7c19
R10: fffffbfff1ff7c19 R11: 1ffffffff1ff7c18 R12: 0000000000004624
R13: dffffc0000000000 R14: ffffc9000185e120 R15: ffffffff8d33df00
 rcu_read_unlock include/linux/rcupdate.h:769 [inline]
 inet_twsk_purge+0x707/0x810 net/ipv4/inet_timewait_sock.c:309
 ops_exit_list net/core/net_namespace.c:177 [inline]
 cleanup_net+0x77b/0xb80 net/core/net_namespace.c:635
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 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 10500 jiffies! g19153 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:28064 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x15c/0x280 kernel/time/timer.c:1914
 rcu_gp_fqs_loop+0x29e/0x11b0 kernel/rcu/tree.c:1972
 rcu_gp_kthread+0x98/0x350 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:
NMI backtrace for cpu 0
CPU: 0 PID: 4295 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <IRQ>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 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+0x10c8/0x1220 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+0x831/0x1110 kernel/rcu/tree.c:2619
 update_process_times+0x193/0x200 kernel/time/timer.c:1818
 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+0x4fe/0xc40 kernel/time/hrtimer.c:1749
 hrtimer_interrupt+0x3bb/0x8d0 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:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0xb98/0xd70 kernel/smp.c:969
Code: 89 de 83 e6 01 31 ff e8 66 49 0b 00 83 e3 01 75 07 e8 fc 45 0b 00 eb 43 f3 90 48 b8 00 00 00 00 00 fc ff df 41 0f b6 44 05 00 <84> c0 75 11 41 f7 04 24 01 00 00 00 74 1e e8 d5 45 0b 00 eb d9 44
RSP: 0018:ffffc9000336fb00 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88802bb53b80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000336fc40 R08: dffffc0000000000 R09: fffffbfff1ff7c24
R10: fffffbfff1ff7c24 R11: 1ffffffff1ff7c23 R12: ffff8880b91405c8
R13: 1ffff110172280b9 R14: ffff8880b903b3c0 R15: 0000000000000001
 on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1134
 kill_bdev block/bdev.c:76 [inline]
 blkdev_flush_mapping+0x178/0x340 block/bdev.c:659
 blkdev_put_whole block/bdev.c:690 [inline]
 blkdev_put+0x4d1/0x7d0 block/bdev.c:957
 blkdev_close+0x76/0xa0 block/fops.c:478
 __fput+0x234/0x930 fs/file_table.c:311
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 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: 0033:0x7f358afce407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffd6b005040 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007f358aee0880 RCX: 00007f358afce407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 00007f358aee06e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
R13: 0000564d7b9f8410 R14: 0000000000000008 R15: 0000564d7ba076d0
 </TASK>
vkms_vblank_simulate: vblank timer overrun

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/05 22:02 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in keyctl
* Struck through repros no longer work on HEAD.