INFO: rcu detected stall in sys_getpid (2)

Status: upstream: reported C repro on 2024/11/30 21:19
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+4f1638fef5ef98110679@syzkaller.appspotmail.com
First crash: 626d, last: 16d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/09/21 linux-5.15.y (ToT) 43bb85222e53 C [report] INFO: rcu detected stall in schedule_timeout
2025/09/21 upstream (ToT) 2d5bd41a4505 C Didn't crash
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: rcu detected stall in sys_getpid (3) 1 syz, C 6 20h25m 90d 0/3 upstream: reported C repro on 2026/05/20 20:58
upstream INFO: rcu detected stall in sys_getpid kernel 1 5 241d 391d 0/29 auto-obsoleted due to no activity on 2026/03/20 23:07
linux-6.6 INFO: rcu detected stall in sys_getpid origin:lts-only 1 syz, C inconclusive 11 16d 346d 0/2 upstream: reported C repro on 2025/09/06 16:11
linux-5.15 INFO: rcu detected stall in sys_getpid 1 1 783d 783d 0/3 auto-obsoleted due to no activity on 2024/10/04 19:18
linux-6.1 INFO: rcu detected stall in sys_getpid 1 1 481d 481d 0/3 auto-obsoleted due to no activity on 2025/08/03 12:49
linux-6.1 INFO: rcu detected stall in sys_getpid (2) 1 2 199d 259d 0/3 auto-obsoleted due to no activity on 2026/05/12 11:26
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/06/07 08:17 17m retest repro linux-5.15.y report log
2026/06/07 08:17 18m retest repro linux-5.15.y report log
2026/05/28 04:43 20m retest repro linux-5.15.y report log
2026/03/17 23:44 12m retest repro linux-5.15.y report log
2026/03/17 20:04 1h40m retest repro linux-5.15.y report log
2026/03/17 20:04 1h34m retest repro linux-5.15.y report log
2025/12/06 13:40 13m retest repro linux-5.15.y report log
2025/12/01 22:02 1h09m retest repro linux-5.15.y report log
2025/12/01 22:02 12m retest repro linux-5.15.y report log
2025/09/27 08:10 15m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (6)
Created Duration User Patch Repo Result
2026/05/13 04:08 13m fix candidate upstream error job log
2026/03/28 06:28 1m fix candidate upstream error job log
2026/02/24 00:39 1m fix candidate upstream error job log
2026/01/24 02:20 1m fix candidate upstream error job log
2025/03/04 18:32 1m fix candidate upstream error job log
2025/01/09 09:40 1h38m fix candidate upstream error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=5549, q=27)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294954824-4294944322), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g5549 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->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:R  running task     stack:28032 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 1
CPU: 1 PID: 4193 Comm: syz-executor870 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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:__rcu_read_unlock+0x0/0xd0 kernel/rcu/tree_plugin.h:415
Code: c0 75 11 ff 03 8b 03 3d 00 00 00 40 7d 02 5b c3 0f 0b eb fa 89 d9 80 e1 07 80 c1 03 38 c1 7c e3 48 89 df e8 42 d7 57 00 eb d9 <41> 57 41 56 41 55 41 54 53 49 bf 00 00 00 00 00 fc ff df 65 48 8b
RSP: 0018:ffffc90002ecfed8 EFLAGS: 00000293
RAX: ffffffff814ec8a1 RBX: 000000000000105c RCX: ffff888079588000
RDX: 0000000000000000 RSI: ffffffff8a59a860 RDI: ffffffff8a59a820
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff1ff7a19
R10: fffffbfff1ff7a19 R11: 1ffffffff1ff7a18 R12: dffffc0000000000
R13: ffff88801f6b0b40 R14: 0000000000000000 R15: ffff88801f6b0c18
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 __task_pid_nr_ns+0x34e/0x420 kernel/pid.c:501
 task_tgid_vnr include/linux/sched.h:1585 [inline]
 __ia32_sys_getpid+0x19/0x20 kernel/sys.c:945
 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: 0033:0x7feed1b98407
Code: 0b e9 68 fe ff ff 48 83 c4 18 48 8d 3d f2 ff 08 00 5b 5d 41 5c 41 5d 41 5e 41 5f e9 03 d8 fd ff 0f 1f 00 b8 27 00 00 00 0f 05 <c3> 0f 1f 84 00 00 00 00 00 31 f6 31 ff e9 87 df 02 00 0f 1f 80 00
RSP: 002b:00007feed1b59b88 EFLAGS: 00000206 ORIG_RAX: 0000000000000027
RAX: ffffffffffffffda RBX: 00007feed1b59cf0 RCX: 00007feed1b98407
RDX: 00007feed1b59bc0 RSI: 00007feed1b59cf0 RDI: 0000000000000021
RBP: 0000000000000000 R08: 00007feed1b5a6c0 R09: 00007feed1b5a6c0
R10: 0000000000000000 R11: 0000000000000206 R12: 00007feed1c2330c
R13: 0000000000000000 R14: 00007ffc41b218c0 R15: 00007ffc41b219a8
 </TASK>

Crashes (24):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/25 11:58 linux-5.15.y ac56c046adf4 c0460fcd .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/09/13 08:06 linux-5.15.y 43bb85222e53 e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2024/11/30 21:18 linux-5.15.y 0a51d2d4527b 68914665 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_getpid
2026/08/02 16:42 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/06/15 07:16 linux-5.15.y dc027a595035 1d2f3589 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/06/11 07:16 linux-5.15.y dc027a595035 b754d2d8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/03/03 19:11 linux-5.15.y 3330a8d33e08 4180d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/02/22 07:26 linux-5.15.y 3330a8d33e08 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/02/22 07:24 linux-5.15.y 3330a8d33e08 6e7b5511 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/02/12 14:06 linux-5.15.y e45d5d41c134 76a109e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/02/10 19:50 linux-5.15.y 7b232985052f 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/02/02 18:26 linux-5.15.y 9eec9a14ee10 018ebef2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/01/30 18:24 linux-5.15.y 9eec9a14ee10 ae7dc18c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2026/01/08 02:00 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_getpid
2025/12/12 23:03 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_getpid
2025/12/09 06:22 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_getpid
2025/11/13 11:27 linux-5.15.y cc5ec8769306 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/11/02 12:58 linux-5.15.y cc5ec8769306 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/10/27 00:28 linux-5.15.y ac56c046adf4 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/10/20 21:41 linux-5.15.y ac56c046adf4 d422939c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/09/12 01:52 linux-5.15.y 43bb85222e53 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/06/18 09:15 linux-5.15.y 1c700860e8bc e77fae15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/06/01 05:25 linux-5.15.y 98f47d0e9b8c 3d2f584d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_getpid
2025/05/23 13:31 linux-5.15.y 98f47d0e9b8c fa44301a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_getpid
* Struck through repros no longer work on HEAD.