syzbot


INFO: rcu detected stall in kthread

Status: upstream: reported on 2025/03/13 04:55
Reported-by: syzbot+[email protected]
First crash: 87d, last: 87d
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in kthread mm 1 2462d 2462d 0/28 closed as invalid on 2018/09/10 16:00
upstream INFO: rcu detected stall in kthread (3) kernel 12 93d 402d 0/28 auto-obsoleted due to no activity on 2025/06/05 06:00
upstream INFO: rcu detected stall in kthread (2) kernel 11 2369d 2457d 0/28 closed as dup on 2019/01/02 16:35
linux-4.19 INFO: rcu detected stall in kthread 2 1344d 1377d 0/1 auto-closed as invalid on 2022/01/30 14:43

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=9645, q=151)
rcu: All QSes seen, last rcu_preempt kthread activity 10502 (4294958125-4294947623), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10502 jiffies! g9645 f0x2 RCU_GP_INIT(4) ->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:26816 pid:   15 ppid:     2 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5027 [inline]
 __schedule+0x12c4/0x45b0 kernel/sched/core.c:6373
 preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6777
 irqentry_exit+0x53/0x80 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:rcu_gp_fqs_loop+0x91/0x1080 kernel/rcu/tree.c:1955
Code: 48 c1 e9 03 48 b8 f1 f1 f1 f1 00 00 00 f3 4a 89 04 31 48 89 4c 24 48 42 c7 44 31 08 f3 f3 f3 f3 45 31 ff 80 3d a3 f6 45 0b 00 <41> 0f 95 c7 41 c1 e7 02 48 8d 84 24 c8 00 00 00 b1 01 89 4c 24 14
RSP: 0018:ffffc90000d47ca0 EFLAGS: 00000246
RAX: f3000000f1f1f1f1 RBX: 0000000000000000 RCX: 1ffff920001a8fa8
RDX: ffff88813ff23b80 RSI: ffffffff8aab3e20 RDI: ffffffff8af9f2c0
RBP: ffffc90000d47df0 R08: ffffffff81870420 R09: fffffbfff1964791
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffc90000d47e60
R13: ffffc90000d47d60 R14: dffffc0000000000 R15: 0000000000000000
 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:
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4568 Comm: syz.4.79 Not tainted 5.15.178-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:arch_static_branch arch/x86/include/asm/jump_label.h:27 [inline]
RIP: 0010:static_key_false include/linux/jump_label.h:212 [inline]
RIP: 0010:native_write_msr arch/x86/include/asm/msr.h:156 [inline]
RIP: 0010:wrmsr arch/x86/include/asm/msr.h:263 [inline]
RIP: 0010:native_apic_msr_write+0x35/0x50 arch/x86/include/asm/apic.h:208
Code: 74 2a 83 ff 30 74 25 eb 10 81 ff d0 00 00 00 74 1b 81 ff e0 00 00 00 74 13 c1 ef 04 81 c7 00 08 00 00 89 f9 89 f0 31 d2 0f 30 <66> 90 c3 89 f6 31 d2 e9 ff a1 fe 02 66 2e 0f 1f 84 00 00 00 00 00
RSP: 0018:ffffc900033cf8c0 EFLAGS: 00000046
RAX: 000000000000003e RBX: ffffffff8c5cc9c8 RCX: 0000000000000838
RDX: 0000000000000000 RSI: 000000000000003e RDI: 0000000000000838
RBP: 0000000000000020 R08: ffffffff817291a8 R09: fffffbfff1c150ee
R10: 0000000000000000 R11: dffffc0000000001 R12: 000000000000003e
R13: dffffc0000000000 R14: 000000000000003e R15: dffffc0000000000
FS:  00007f14834ac6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000040000006b000 CR3: 0000000024cd1000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 apic_write arch/x86/include/asm/apic.h:395 [inline]
 lapic_next_event+0x5b/0x70 arch/x86/kernel/apic/apic.c:468
 clockevents_program_min_delta+0x1ae/0x410 kernel/time/clockevents.c:248
 hrtimer_start_range_ns+0xada/0xc80 kernel/time/hrtimer.c:1302
 posixtimer_rearm+0x1ad/0x3f0 kernel/time/posix-timers.c:328
 dequeue_signal+0x1ed/0x520 kernel/signal.c:696
 get_signal+0x52e/0x14e0 kernel/signal.c:2781
 arch_do_signal_or_restart+0xc3/0x1890 arch/x86/kernel/signal.c:867
 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: 0033:0x7f1485643167
Code: ff ff 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
RSP: 002b:00007f14834ac038 EFLAGS: 00000246
RAX: 0000000000000113 RBX: 00007f148585bfa0 RCX: 00007f1485643169
RDX: 0000000000000008 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f14856c42a0 R08: 0000000008000f28 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f148585bfa0 R15: 00007fffbad017c8
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/13 04:55 linux-5.15.y c16c81c81336 1a5d9317 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in kthread
* Struck through repros no longer work on HEAD.
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