INFO: rcu detected stall in vga_arb_release

Status: upstream: reported C repro on 2025/09/09 21:11
Subsystems: pci
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+e333f6ae9120efd3294a@syzkaller.appspotmail.com
First crash: 410d, last: 3d12h
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log)
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
bf7a9da9 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: rcu detected stall in vga_arb_release 2026/05/19 20:40 2026/05/19 20:40 2026/05/19 21:31 1d9407ad
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [pci?] INFO: rcu detected stall in vga_arb_release 0 (1) 2025/09/09 21:11
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2026/09/25 04:39 21m retest repro upstream report job log log
2026/06/24 17:19 22m retest repro upstream log
2026/04/08 02:00 20m retest repro upstream report log
2026/01/27 21:42 21m retest repro upstream report log
2025/09/24 03:10 16m retest repro upstream report log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/11/18 21:25 0m bisect fix upstream error
2025/10/15 06:42 2h46m bisect fix upstream OK (0) job log log

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P7407
rcu: 	(detected by 0, t=10502 jiffies, g=11429, q=1533 ncpus=2)
task:syz-executor248 state:R  running task     stack:26952 pid:7407  tgid:7405  ppid:5601   task_flags:0x40044c flags:0x00080001
Call Trace:
 <IRQ>
 sched_show_task+0x4aa/0x5f0 kernel/sched/core.c:8250
 rcu_print_detail_task_stall_rnp kernel/rcu/tree_stall.h:292 [inline]
 print_other_cpu_stall+0xfbf/0x1350 kernel/rcu/tree_stall.h:683
 check_cpu_stall kernel/rcu/tree_stall.h:860 [inline]
 rcu_pending kernel/rcu/tree.c:3744 [inline]
 rcu_sched_clock_irq+0x9fe/0x10e0 kernel/rcu/tree.c:2749
 update_process_times+0x234/0x2d0 kernel/time/timer.c:2475
 tick_sched_handle kernel/time/tick-sched.c:296 [inline]
 tick_nohz_handler+0x38f/0x6b0 kernel/time/tick-sched.c:317
 __run_hrtimer kernel/time/hrtimer.c:2074 [inline]
 __hrtimer_run_queues+0x3a0/0xaf0 kernel/time/hrtimer.c:2131
 hrtimer_interrupt+0x4c2/0xa80 kernel/time/hrtimer.c:2250
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline]
 __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
 sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:211 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x47/0x80 kernel/locking/spinlock.c:221
Code: f7 e8 ed bf 44 f6 f7 c3 00 02 00 00 74 05 e8 c0 1e 71 f6 9c 58 a9 00 02 00 00 75 29 f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 44 c6 36 f6 65 48 8b 05 ac 43 48 08 48 85 c0 74 18 5b 41 5e c3
RSP: 0018:ffffc900056b7828 EFLAGS: 00000206
RAX: 0000000000000006 RBX: 0000000000000246 RCX: 8000000000000001
RDX: 0000000000000006 RSI: ffffffff8d8c0005 RDI: 0000000000000001
RBP: ffffc900056b7930 R08: ffffffff90b2397f R09: 1ffffffff216472f
R10: dffffc0000000000 R11: fffffbfff2164730 R12: dffffc0000000000
R13: 1ffff92000ad6f10 R14: ffffffff8fa20080 R15: 0000000000000246
 unlock_rt_mutex_safe kernel/locking/rtmutex.c:350 [inline]
 rt_mutex_slowunlock+0x4ee/0xa30 kernel/locking/rtmutex.c:1467
 rt_spin_unlock+0x10f/0x200 kernel/locking/spinlock_rt.c:84
 spin_unlock_irqrestore include/linux/spinlock_rt.h:141 [inline]
 vga_put drivers/pci/vgaarb.c:562 [inline]
 vga_arb_release+0x273/0x5b0 drivers/pci/vgaarb.c:1437
 __fput+0x41f/0xa80 fs/file_table.c:512
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x73a/0x2360 kernel/exit.c:986
 do_group_exit+0x22d/0x2f0 kernel/exit.c:1129
 get_signal+0x121b/0x12c0 kernel/signal.c:3112
 arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x10e/0x770 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:343 [inline]
 do_syscall_64+0x328/0x520 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f724d69bfe9
Code: Unable to access opcode bytes at 0x7f724d69bfbf.
RSP: 002b:00007f724d6531d8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007f724d74cb58 RCX: 00007f724d69bfe9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f724d74cb58
RBP: 00007f724d74cb50 R08: 37203a6b63617473 R09: 37203a6b63617473
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f724d74cb5c
R13: 0000200000000080 R14: 0000200000000480 R15: 00002000000000c0
 </TASK>

Crashes (17):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/12 22:55 upstream 24a19b953e2a 745a967f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2025/09/09 07:58 upstream f777d1112ee5 d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/10/20 22:34 upstream f47d223627f8 df8746fb .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/10/12 19:37 upstream 24a19b953e2a 745a967f .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/07/29 22:53 upstream fc02acf6ac0c 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/07/04 04:33 upstream 71dfdfb0209b fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/07/04 04:26 upstream 71dfdfb0209b fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/06/08 13:01 upstream 4549871118cf cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/05/14 06:28 upstream e1914add2799 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/04/22 00:29 upstream 4ee64205ffaa 0b6ab7ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/02/18 13:57 upstream c22e26bd0906 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/02/15 11:46 upstream c22e26bd0906 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2025/12/12 01:37 upstream d358e5254674 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: rcu detected stall in vga_arb_release
2026/07/07 23:28 linux-next 5c73cd9f0819 88a4b44c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in vga_arb_release
2026/06/08 09:48 linux-next f7af91adc230 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in vga_arb_release
2026/05/14 05:09 linux-next e98d21c170b0 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in vga_arb_release
2026/05/03 23:59 linux-next b9303e6bff70 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce INFO: rcu detected stall in vga_arb_release
* Struck through repros no longer work on HEAD.