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INFO: rcu detected stall in sys_futex (2)

Status: upstream: reported syz repro on 2024/06/05 16:49
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+6ceb9abf06f08ceec1d2@syzkaller.appspotmail.com
First crash: 348d, last: 3d00h
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/01/05 linux-5.15.y (ToT) 91786f140358 C [report] INFO: rcu detected stall in corrupted
2025/01/05 upstream (ToT) ab75170520d4 C Didn't crash
▶ ▼ Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in sys_futex (7) kernel syz error 79 18d 329d 0/28 upstream: reported syz repro on 2024/06/24 16:48
upstream INFO: rcu detected stall in sys_futex (3) kernel 959 1958d 2007d 0/28 auto-closed as invalid on 2020/03/08 12:44
upstream INFO: rcu detected stall in sys_futex (2) kernel 6 2126d 2271d 0/28 auto-closed as invalid on 2019/10/25 14:11
upstream INFO: rcu detected stall in sys_futex (4) kernel 1 1208d 1208d 0/28 closed as invalid on 2022/02/08 10:00
upstream INFO: rcu detected stall in sys_futex kernel 1 2332d 2332d 0/28 closed as invalid on 2018/12/31 04:10
linux-5.15 INFO: rcu detected stall in sys_futex 4 504d 679d 0/3 auto-obsoleted due to no activity on 2024/04/10 17:08
linux-6.1 INFO: rcu detected stall in sys_futex origin:lts-only syz done 19 14d 684d 0/3 upstream: reported syz repro on 2023/07/05 11:35
upstream INFO: rcu detected stall in sys_futex (5) kernel 12 938d 1183d 0/28 auto-obsoleted due to no activity on 2023/02/12 18:33
upstream INFO: rcu detected stall in sys_futex (6) kernel 10 507d 743d 0/28 auto-obsoleted due to no activity on 2024/03/29 00:57
upstream INFO: rcu detected stall in futex kvm 1 1583d 1583d 0/28 auto-closed as invalid on 2021/04/17 19:46
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/03/16 10:05 15m retest repro linux-5.15.y OK log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/03/05 06:47 16m fix candidate upstream error job log
2025/01/18 16:59 22m fix candidate upstream 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): P3546/1:b..l
	(detected by 1, t=10503 jiffies, g=65773, q=194)
task:udevd           state:R  running task     stack:22176 pid: 3546 ppid:     1 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5029 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6375
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6779
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_reschedule_ipi+0x16/0x20 arch/x86/include/asm/idtentry.h:681
RIP: 0010:lock_acquire+0x296/0x4f0 kernel/locking/lockdep.c:5627
Code: 00 66 43 c7 44 25 15 00 00 43 c6 44 25 17 00 65 48 8b 04 25 28 00 00 00 48 3b 84 24 00 01 00 00 0f 85 52 02 00 00 48 8d 65 d8 <5b> 41 5c 41 5d 41 5e 41 5f 5d c3 65 8b 05 88 95 9f 7e 85 c0 75 9d
RSP: 0018:ffffc90002eaf520 EFLAGS: 00000246
RAX: 98a07952198d1800 RBX: 1ffff920005d5e8c RCX: 1ffff920005d5e2c
RDX: dffffc0000000000 RSI: ffffffff8aab3d00 RDI: ffffffff8af9fa80
RBP: ffffc90002eaf548 R08: dffffc0000000000 R09: fffffbfff2131e19
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920005d5e88
R13: dffffc0000000000 R14: ffffc90002eaf460 R15: 0000000000000246
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:312
 rcu_read_lock include/linux/rcupdate.h:739 [inline]
 dput+0x35/0x1a0 fs/dcache.c:879
 step_into+0x352/0xe90 fs/namei.c:1815
 walk_component+0x359/0x610 fs/namei.c:1982
 link_path_walk+0x642/0xd90 fs/namei.c:-1
 path_openat+0x249/0x2f20 fs/namei.c:3738
 do_filp_open+0x21c/0x460 fs/namei.c:3769
 do_sys_openat2+0x13b/0x4f0 fs/open.c:1253
 do_sys_open fs/open.c:1269 [inline]
 __do_sys_openat fs/open.c:1285 [inline]
 __se_sys_openat fs/open.c:1280 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1280
 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: 0033:0x7fa173b10477
RSP: 002b:00007ffeb4d17218 EFLAGS: 00000287 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000561c295fbec0 RCX: 00007fa173b10477
RDX: 0000000000090800 RSI: 0000561c295f0510 RDI: 00000000ffffff9c
RBP: 0000561c2969b600 R08: 0000000000090800 R09: 0000561c295f0510
R10: 0000000000000000 R11: 0000000000000287 R12: 0000561c295f0510
R13: 00000000000000fd R14: 0000561bebca71c4 R15: 0000000000000000
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10541 jiffies! g65773 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=1 timer-softirq=34566
rcu: rcu_preempt kthread starved for 10544 jiffies! g65773 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:25752 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5029 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6375
 schedule+0x11b/0x1f0 kernel/sched/core.c:6458
 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:287
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 15397 Comm: syz.2.3416 Not tainted 5.15.179-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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:1688 [inline]
 __hrtimer_run_queues+0x55b/0xcf0 kernel/time/hrtimer.c:1752
 hrtimer_interrupt+0x392/0x980 kernel/time/hrtimer.c:1814
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 [inline]
 __sysvec_apic_timer_interrupt+0x13b/0x4b0 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:raw_spin_rq_unlock_irq+0x19/0x80 kernel/sched/sched.h:1339
Code: 38 c1 7c cb 4c 89 f7 e8 15 c2 70 00 eb c1 0f 1f 00 41 57 41 56 53 48 89 fb 66 90 48 89 df e8 9e d0 ef 08 e8 39 4e 2d 00 fb 5b <41> 5e 41 5f c3 49 bf 00 00 00 00 00 fc ff df 4c 8d b3 58 0d 00 00
RSP: 0018:ffffc9000356f708 EFLAGS: 00000286
RAX: 72bf1ae7385d2c00 RBX: ffff8880b8f3a300 RCX: ffffffff96a95f03
RDX: dffffc0000000000 RSI: ffffffff8aab2a60 RDI: ffffffff8af9fa80
RBP: ffffc9000356f900 R08: ffffffff81871b70 R09: ffffed10171e7461
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888024cc3b80
R13: dffffc0000000000 R14: ffff888024cc3b80 R15: ffffffff8c5c63b0
 __schedule+0x1462/0x45b0 kernel/sched/core.c:6381
 schedule+0x11b/0x1f0 kernel/sched/core.c:6458
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x25b/0x480 kernel/futex/core.c:2863
 futex_wait+0x2f8/0x740 kernel/futex/core.c:2964
 do_futex+0x1414/0x1810 kernel/futex/core.c:3982
 __do_sys_futex kernel/futex/core.c:4059 [inline]
 __se_sys_futex+0x407/0x490 kernel/futex/core.c:4040
 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: 0033:0x7fe30e645169
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:00007fe30c4ae0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: ffffffffffffffda RBX: 00007fe30e85dfa8 RCX: 00007fe30e645169
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fe30e85dfa8
RBP: 00007fe30e85dfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe30e85dfac
R13: 0000000000000000 R14: 00007ffca20c1bb0 R15: 00007ffca20c1c98
 </TASK>

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/08 15:43 linux-5.15.y 0c935c049b5c a775275d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2025/03/19 14:24 linux-5.15.y 0c935c049b5c 8d0a2921 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2025/01/02 00:57 linux-5.15.y 91786f140358 d3ccff63 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_futex
2025/01/01 17:38 linux-5.15.y 91786f140358 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_futex
2024/12/14 04:24 linux-5.15.y 0a51d2d4527b 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/11/13 09:14 linux-5.15.y 3c17fc483905 62026c85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/10/12 08:25 linux-5.15.y 3a5928702e71 084d8178 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/10/06 13:38 linux-5.15.y 3a5928702e71 d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in sys_futex
2024/09/23 11:34 linux-5.15.y 3a5928702e71 89298aad .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/08/13 03:25 linux-5.15.y 7e89efd3ae1c 7b0f4b46 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/08/03 03:41 linux-5.15.y 7e89efd3ae1c 1786a2a8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/06/12 14:06 linux-5.15.y c61bd26ae81a f815599d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/06/05 16:49 linux-5.15.y c61bd26ae81a 5aa1a7c9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_futex
2024/08/22 15:56 linux-5.15.y fa93fa65db6e ca02180f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_futex
2025/05/17 10:42 linux-5.15.y 3b8db0e4f263 f41472b0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in futex
2025/05/14 20:58 linux-5.15.y 3b8db0e4f263 a4fa04ef .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in futex
2025/04/16 06:19 linux-5.15.y f7347f400572 a95239b1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in futex
* Struck through repros no longer work on HEAD.