syzbot

 sign-in | mailing list | source | docs
🐞 Open [712]
🐞 Fixed [73]
🐞 Invalid [882]
⬇ Missing Backports [114]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

INFO: rcu detected stall in sys_rt_sigreturn

Status: upstream: reported C repro on 2024/04/01 14:20
Bug presence: origin:lts-only
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+45c71f99506e933fd050@syzkaller.appspotmail.com
First crash: 431d, last: 1h34m
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/05/29 linux-5.15.y (ToT) 98f47d0e9b8c C [report] INFO: rcu detected stall in syscall_exit_to_user_mode
2025/05/29 upstream (ToT) 90b83efa6701 C Didn't crash
▶ ▼ Last patch testing requests (8)
Created Duration User Patch Repo Result
2025/04/06 22:09 13m retest repro linux-5.15.y report log
2025/04/06 22:09 13m retest repro linux-5.15.y report log
2025/04/06 22:09 16m retest repro linux-5.15.y report log
2025/04/06 22:09 13m retest repro linux-5.15.y report log
2025/04/06 22:09 24m retest repro linux-5.15.y report log
2025/03/31 05:27 13m retest repro linux-5.15.y report log
2025/03/14 11:39 16m retest repro linux-5.15.y report log
2025/03/14 11:39 19m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (5)
Created Duration User Patch Repo Result
2025/04/22 05:15 1m fix candidate upstream error job log
2025/03/09 10:09 3m fix candidate upstream error job log
2024/11/19 08:24 1m fix candidate upstream error job log
2024/10/15 08:39 0m fix candidate upstream error job log
2024/05/02 14:56 52m bisect fix linux-5.15.y error job log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
	(detected by 1, t=10502 jiffies, g=5441, q=44)
rcu: All QSes seen, last rcu_preempt kthread activity 10499 (4294953956-4294943457), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10500 jiffies! g5441 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:5030 [inline]
 __schedule+0x11b8/0x43b0 kernel/sched/core.c:6376
 schedule+0x11b/0x1e0 kernel/sched/core.c:6459
 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: 4195 Comm: syz-executor289 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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:3932 [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:1690 [inline]
 __hrtimer_run_queues+0x4fe/0xc40 kernel/time/hrtimer.c:1754
 hrtimer_interrupt+0x3bb/0x8d0 kernel/time/hrtimer.c:1816
 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:should_resched arch/x86/include/asm/preempt.h:103 [inline]
RIP: 0010:__local_bh_enable_ip+0x132/0x1b0 kernel/softirq.c:390
Code: 8a e8 12 dd 58 08 65 66 8b 05 ea 37 bb 7e 66 85 c0 75 54 bf 01 00 00 00 e8 6b fe 08 00 e8 66 7e 35 00 fb 65 8b 05 d6 0e ba 7e <85> c0 75 05 e8 85 19 b8 ff 48 c7 04 24 0e 36 e0 45 4b c7 04 37 00
RSP: 0018:ffffc90002f9faa0 EFLAGS: 00000286
RAX: 0000000080000000 RBX: 0000000000000200 RCX: 80a9630a2b9e2c00
RDX: dffffc0000000000 RSI: ffffffff8a0b11c0 RDI: ffffffff8a59a700
RBP: ffffc90002f9fb30 R08: dffffc0000000000 R09: ffffed10035f8771
R10: ffffed10035f8771 R11: 1ffff110035f8770 R12: ffffffff812bdb95
R13: 0000000000000000 R14: dffffc0000000000 R15: 1ffff920005f3f54
 fpregs_unlock arch/x86/include/asm/fpu/api.h:78 [inline]
 restore_fpregs_from_user arch/x86/kernel/fpu/signal.c:300 [inline]
 __fpu_restore_sig arch/x86/kernel/fpu/signal.c:334 [inline]
 fpu__restore_sig+0x785/0xf50 arch/x86/kernel/fpu/signal.c:466
 restore_sigcontext arch/x86/kernel/signal.c:139 [inline]
 __ia32_sys_rt_sigreturn+0x649/0x790 arch/x86/kernel/signal.c:674
 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: 0033:0x7f5525dd4899
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 19 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff32aa67c8 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 00007f5525dd4899
RDX: 000020000006b000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 00007f5525d94990 R09: 00007f5525d94990
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5525e3233c
R13: 00007f5525e2c106 R14: 00007fff32aa6800 R15: 0000000000000000
 </TASK>

Crashes (51):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/27 06:43 linux-5.15.y 98f47d0e9b8c 874a1386 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/06/03 21:12 linux-5.15.y 98f47d0e9b8c a30356b7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/06/03 18:31 linux-5.15.y 98f47d0e9b8c a30356b7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/30 07:28 linux-5.15.y 98f47d0e9b8c 3d2f584d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/27 04:42 linux-5.15.y 98f47d0e9b8c 874a1386 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/16 05:04 linux-5.15.y 3b8db0e4f263 cfde8269 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/13 11:14 linux-5.15.y 3b8db0e4f263 f6671af7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/11 01:45 linux-5.15.y 3b8db0e4f263 77908e5f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/07 12:41 linux-5.15.y 16fdf2c7111b 350f4ffc .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/04/17 04:23 linux-5.15.y f7347f400572 a95239b1 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/04/14 20:48 linux-5.15.y f7347f400572 0bd6db41 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/02/27 18:10 linux-5.15.y c16c81c81336 6a8fcbc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/01/12 14:15 linux-5.15.y 4735586da88e 6dbc6a9b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/12/13 04:52 linux-5.15.y 0a51d2d4527b 530e80f8 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/12/07 18:32 linux-5.15.y 0a51d2d4527b 9ac0fdc6 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/09/19 12:16 linux-5.15.y 3a5928702e71 c673ca06 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/04/01 14:20 linux-5.15.y 9465fef4ae35 6baf5069 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/05/12 00:13 linux-5.15.y 3b8db0e4f263 77908e5f .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/04/12 09:52 linux-5.15.y f7347f400572 0bd6db41 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/04/10 10:05 linux-5.15.y 0c935c049b5c 988b336c .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/03/15 10:16 linux-5.15.y 0c935c049b5c e2826670 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/10/21 00:37 linux-5.15.y 584a40a22cb9 cd6fc0a3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/10/20 10:57 linux-5.15.y 584a40a22cb9 cd6fc0a3 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/09/19 02:56 linux-5.15.y 3a5928702e71 c673ca06 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2025/06/07 06:39 linux-5.15.y 1c700860e8bc 4826c28e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/06/01 10:23 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_rt_sigreturn
2025/05/30 00:22 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_rt_sigreturn
2025/05/18 14:49 linux-5.15.y a68c15152131 f41472b0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/13 22:00 linux-5.15.y 3b8db0e4f263 7344edeb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/09 08:29 linux-5.15.y 16fdf2c7111b bb813bcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/08 02:29 linux-5.15.y 16fdf2c7111b dbf35fa1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/05 19:49 linux-5.15.y 16fdf2c7111b 6ca47dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/05 19:48 linux-5.15.y 16fdf2c7111b 6ca47dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/05 18:30 linux-5.15.y 16fdf2c7111b 6ca47dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/05/03 02:07 linux-5.15.y 16fdf2c7111b b0714e37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/04/30 15:47 linux-5.15.y f7347f400572 85a5a23f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/04/30 04:51 linux-5.15.y f7347f400572 85a5a23f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: rcu detected stall in sys_rt_sigreturn
2025/06/04 21:56 linux-5.15.y 1c700860e8bc e565f08d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/12/05 01:47 linux-5.15.y 0a51d2d4527b b50eb251 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/11/25 06:07 linux-5.15.y 0a51d2d4527b 68da6d95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/10/24 18:48 linux-5.15.y 74cdd62cb470 0d144d1a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/10/12 07:40 linux-5.15.y 3a5928702e71 084d8178 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/10/01 21:29 linux-5.15.y 3a5928702e71 ea2b66a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/09/29 21:17 linux-5.15.y 3a5928702e71 ba29ff75 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/08/26 03:40 linux-5.15.y fa93fa65db6e d7d32352 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/08/17 13:11 linux-5.15.y 7e89efd3ae1c dbc93b08 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/08/14 21:41 linux-5.15.y 7e89efd3ae1c e6b88e20 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/07/05 19:45 linux-5.15.y f45bea23c39c 2a40360c .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/06/28 13:22 linux-5.15.y 4878aadf2d15 6ef39602 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/06/23 23:17 linux-5.15.y 4878aadf2d15 edc5149a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
2024/05/18 17:41 linux-5.15.y 83655231580b c0f1611a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 INFO: rcu detected stall in sys_rt_sigreturn
* Struck through repros no longer work on HEAD.