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INFO: rcu detected stall in try_check_zero (5)

Status: upstream: reported syz repro on 2025/01/02 10:34
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+e671de40c3198d01f2cb@syzkaller.appspotmail.com
First crash: 540d, last: 160d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (5)
ID Workflow Result Correct Bug Created Started Finished Revision Error
6e0771a5-ba53-4400-9c70-0336ddb349dc assessment-security 💥 INFO: rcu detected stall in try_check_zero (5) 2026/06/18 05:38 2026/06/18 05:38 2026/06/18 06:04 b62b3ded1759f79b37600c5ffe2b0a81b919b0b0 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/674dd226d9c6da3d54...
truncated to first 200 bytes; open job for full error
65314b87-454e-4961-b2ee-97b5d2fd925a assessment-security 💥 INFO: rcu detected stall in try_check_zero (5) 2026/06/10 01:30 2026/06/10 01:30 2026/06/10 01:54 c36c07f6c1f2230a36374cbd22235f635e8f9284 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/674dd226d9c6da3d54...
truncated to first 200 bytes; open job for full error
bcbc5748-8a72-49a1-9f90-c1bb94dc76b0 assessment-security 💥 INFO: rcu detected stall in try_check_zero (5) 2026/06/04 03:58 2026/06/04 03:58 2026/06/04 04:15 62fe15281f5011cd203d8845b8767b10e7443aa5 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/674dd226d9c6da3d54...
truncated to first 200 bytes; open job for full error
7a370908-c736-462e-9f12-6e5394f20213 assessment-security 💥 INFO: rcu detected stall in try_check_zero (5) 2026/06/01 19:05 2026/06/01 19:05 2026/06/01 19:30 386cc6dacdf7e3ebce9507beed6755d7e999554d 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/674dd226d9c6da3d54...
truncated to first 200 bytes; open job for full error
dcda4b83-93db-4dbb-a94d-604bfc8bac87 assessment-security 💥 INFO: rcu detected stall in try_check_zero (5) 2026/05/17 23:17 2026/05/17 23:17 2026/05/17 23:49 de5aae85e5f28e2fa1c7deefcc24fe286abe5140 
failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/674dd226d9c6da3d54...
truncated to first 200 bytes; open job for full error
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] INFO: rcu detected stall in try_check_zero (5) 0 (1) 2025/01/02 10:34
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in try_check_zero kernel 1 66 2236d 2678d 0/29 auto-closed as invalid on 2020/09/05 16:29
linux-6.1 INFO: rcu detected stall in try_check_zero (2) origin:lts-only 1 C error 1 126d 126d 0/3 upstream: reported C repro on 2026/02/16 13:40
upstream INFO: rcu detected stall in try_check_zero (2) kernel 1 1 2105d 2105d 0/29 auto-closed as invalid on 2020/12/15 14:13
upstream INFO: rcu detected stall in try_check_zero (3) kernel 1 2 1622d 1625d 0/29 closed as invalid on 2022/02/08 10:10
upstream INFO: rcu detected stall in try_check_zero (4) kernel 1 2 1114d 1181d 0/29 auto-obsoleted due to no activity on 2023/09/02 21:24
linux-6.1 INFO: rcu detected stall in try_check_zero 1 1 584d 584d 0/3 auto-obsoleted due to no activity on 2025/02/23 21:01
▶ ▼ Last patch testing requests (4)
Created Duration User Patch Repo Result
2026/04/23 07:31 46m retest repro upstream report log
2025/11/19 00:41 52m retest repro upstream report log
2025/09/09 23:03 20m retest repro upstream report log
2025/01/12 10:31 18m retest repro upstream report log
▶ ▼ Fix bisection attempts (7)
Created Duration User Patch Repo Result
2026/02/12 05:34 1m bisect fix upstream error job log
2026/01/13 01:08 2h23m bisect fix upstream OK (0) job log log
2025/12/13 15:39 2h09m bisect fix upstream OK (0) job log log
2025/07/01 17:13 3h44m bisect fix upstream OK (0) job log log
2025/05/20 09:12 3h46m bisect fix upstream OK (0) job log log
2025/03/29 04:05 3h37m bisect fix upstream OK (0) job log log
2025/02/26 17:44 2h03m bisect fix upstream OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (2 ticks this GP) idle=bef4/1/0x4000000000000000 softirq=13852/13852 fqs=0
rcu: 	(detected by 1, t=10502 jiffies, g=8201, q=617 ncpus=2)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.13.0-rc4-syzkaller-00078-g059dd502b263 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: rcu_gp process_srcu
RIP: 0010:mark_usage kernel/locking/lockdep.c:4637 [inline]
RIP: 0010:__lock_acquire+0x12c6/0x3c40 kernel/locking/lockdep.c:5180
Code: ff 65 8b 05 24 fe 8b 7e 85 c0 0f 85 d7 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 7c 24 40 48 89 fa 48 c1 ea 03 0f b6 14 02 <48> 89 f8 83 e0 07 83 c0 03 38 d0 7c 09 84 d2 74 05 e8 e4 36 86 00
RSP: 0018:ffffc90000007b38 EFLAGS: 00000803
RAX: dffffc0000000000 RBX: ffff88801c6b53fa RCX: 1ffffffff2dd8c62
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff88801c6b5344
RBP: 0000000000000049 R08: 0000000000000000 R09: fffffbfff2dca3bd
R10: ffffffff96e51def R11: 0000000000000004 R12: ffff88801c6b53d1
R13: ffff88801c6b4880 R14: 0000000000000003 R15: ffff88801c6b53d8
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000600 CR3: 000000002d36e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 advance_sched+0xd8/0xc60 net/sched/sch_taprio.c:924
 __run_hrtimer kernel/time/hrtimer.c:1739 [inline]
 __hrtimer_run_queues+0x20a/0xae0 kernel/time/hrtimer.c:1803
 hrtimer_interrupt+0x392/0x8e0 kernel/time/hrtimer.c:1865
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1038 [inline]
 __sysvec_apic_timer_interrupt+0x10f/0x400 arch/x86/kernel/apic/apic.c:1055
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1049
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:preempt_latency_start kernel/sched/core.c:5828 [inline]
RIP: 0010:preempt_count_add+0x52/0x150 kernel/sched/core.c:5854
Code: 3d 1b 6b 9b 7e 0f b6 14 11 38 d0 7c 08 84 d2 0f 85 dd 00 00 00 8b 15 9d 5a 1c 19 85 d2 75 0b 65 8b 05 fa 6a 9b 7e 3c f4 77 6b <65> 8b 05 ef 6a 9b 7e 25 ff ff ff 7f 39 c3 74 07 5b 5d c3 cc cc cc
RSP: 0018:ffffc900000e7b20 EFLAGS: 00000213
RAX: 0000000080000001 RBX: 0000000000000001 RCX: 1ffffffff3509914
RDX: 0000000000000000 RSI: ffffffff8bd1ed20 RDI: 0000000000000001
RBP: 00000051629f0d2a R08: 0000000000000001 R09: ffffed10170e8d59
R10: ffff8880b8746acf R11: 0000000000000002 R12: 0000000000000000
R13: 00000000000036b2 R14: ffffffff9a880640 R15: 000000000000104e
 delay_tsc+0x3c/0xc0 arch/x86/lib/delay.c:79
 udelay include/asm-generic/delay.h:64 [inline]
 try_check_zero+0x3c6/0x5a0 kernel/rcu/srcutree.c:1112
 srcu_advance_state kernel/rcu/srcutree.c:1742 [inline]
 process_srcu+0x575/0x1720 kernel/rcu/srcutree.c:1851
 process_one_work+0x9c5/0x1ba0 kernel/workqueue.c:3229
 process_scheduled_works kernel/workqueue.c:3310 [inline]
 worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
rcu: rcu_preempt kthread timer wakeup didn't happen for 10501 jiffies! g8201 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
rcu: 	Possible timer handling issue on cpu=0 timer-softirq=5774
rcu: rcu_preempt kthread starved for 10502 jiffies! g8201 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->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:I stack:27600 pid:17    tgid:17    ppid:2      flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5369 [inline]
 __schedule+0xe58/0x5ad0 kernel/sched/core.c:6756
 __schedule_loop kernel/sched/core.c:6833 [inline]
 schedule+0xe7/0x350 kernel/sched/core.c:6848
 schedule_timeout+0x124/0x280 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2045
 rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2247
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/29 10:31 upstream 059dd502b263 d3ccff63 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in try_check_zero
2025/01/17 21:01 upstream 9bffa1ad25b8 953d1c45 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root INFO: rcu detected stall in try_check_zero
* Struck through repros no longer work on HEAD.