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INFO: rcu detected stall in __tun_chr_ioctl (2)

Status: upstream: reported on 2025/11/23 13:35
Reported-by: syzbot+e51b463bd916f2ba7b55@syzkaller.appspotmail.com
First crash: 234d, last: 1d07h
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in __tun_chr_ioctl mm 1 4 544d 619d 0/29 auto-obsoleted due to no activity on 2025/04/18 05:25
linux-5.15 INFO: rcu detected stall in __tun_chr_ioctl 1 1 496d 496d 0/3 auto-obsoleted due to no activity on 2025/06/14 12:09
linux-6.1 INFO: rcu detected stall in __tun_chr_ioctl 1 3 211d 235d 0/3 auto-obsoleted due to no activity on 2026/03/26 13:49
linux-6.6 INFO: rcu detected stall in __tun_chr_ioctl (2) 1 2 7d06h 13d 0/2 upstream: reported on 2026/07/02 11:58
linux-6.6 INFO: rcu detected stall in __tun_chr_ioctl 1 1 115d 115d 0/2 auto-obsoleted due to no activity on 2026/07/01 00:03
linux-6.1 INFO: rcu detected stall in __tun_chr_ioctl (2) 1 5 25d 109d 0/3 upstream: reported on 2026/03/28 18:58

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=229/1/0x4000000000000000 softirq=7165/7166 fqs=2100 
	(detected by 1, t=10505 jiffies, g=8089, q=1424)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 4635 Comm: syz.2.61 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
RIP: 0010:lock_acquire+0x6/0x400 kernel/locking/lockdep.c:5591
Code: ff 48 c7 c7 88 1e 8b 8d e8 17 39 61 00 e9 29 fb ff ff 66 90 65 8b 05 c1 97 a5 7e a9 00 ff ff 00 0f 95 c0 c3 55 48 89 e5 41 57 <41> 56 41 55 41 54 53 48 83 e4 e0 48 81 ec e0 00 00 00 4c 89 4c 24
RSP: 0018:ffffc90000007150 EFLAGS: 00000046
RAX: ffffffff819a2b6e RBX: ffffffff8c31ef20 RCX: 0000000000000002
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8c31ef20
RBP: ffffc90000007158 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100eee82cc R12: dffffc0000000000
R13: 1ffff92000000e34 R14: dffffc0000000000 R15: ffffc90000007380
FS:  00007f083c8b16c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc9f23d5540 CR3: 000000005e5a9000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:313
 rcu_read_lock include/linux/rcupdate.h:740 [inline]
 __perf_event_output kernel/events/core.c:7800 [inline]
 perf_event_output_forward+0xbc/0x2e0 kernel/events/core.c:7822
 __perf_event_overflow+0x35f/0x550 kernel/events/core.c:9515
 perf_tp_event+0x324/0xbe0 kernel/events/core.c:10047
 perf_trace_run_bpf_submit+0xf3/0x1c0 kernel/events/core.c:10021
 perf_trace_preemptirq_template+0x2aa/0x360 include/trace/events/preemptirq.h:14
 trace_irq_enable_rcuidle+0x108/0x180 include/trace/events/preemptirq.h:40
 trace_hardirqs_on+0x57/0x80 kernel/trace/trace_preemptirq.c:44
 asm_sysvec_irq_work+0x16/0x20 arch/x86/include/asm/idtentry.h:713
RIP: 0010:rcu_read_unlock_special+0x7f/0x4a0 kernel/rcu/tree_plugin.h:674
Code: eb 03 48 b8 f1 f1 f1 f1 f8 f2 f2 f2 4a 89 04 2b 42 c7 44 2b 08 f8 f3 f3 f3 65 44 8b 35 c2 22 9d 7e 41 f7 c6 00 00 f0 00 74 40 <48> c7 44 24 20 0e 36 e0 45 4a c7 04 2b 00 00 00 00 42 c7 44 2b 08
RSP: 0018:ffffc900000077c0 EFLAGS: 00000206
RAX: 2499c51175f64d00 RBX: 1ffff92000000efc RCX: 2499c51175f64d00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a2a40
RBP: ffffc900000078a0 R08: ffffffff901e90cf R09: 1ffffffff203d219
R10: dffffc0000000000 R11: fffffbfff203d21a R12: ffffffff8c323400
R13: dffffc0000000000 R14: 0000000000000246 R15: 0000000000000001
 __rcu_read_unlock+0x78/0xd0 kernel/rcu/tree_plugin.h:422
 rcu_read_unlock include/linux/rcupdate.h:772 [inline]
 netif_receive_skb_list_internal+0x961/0xbd0 net/core/dev.c:5786
 gro_normal_list net/core/dev.c:5939 [inline]
 napi_complete_done+0x37e/0x850 net/core/dev.c:6677
 virtqueue_napi_complete drivers/net/virtio_net.c:357 [inline]
 virtnet_poll+0x8f5/0xe90 drivers/net/virtio_net.c:1624
 __napi_poll+0xbb/0x430 net/core/dev.c:7101
 napi_poll net/core/dev.c:7168 [inline]
 net_rx_action+0x522/0xa80 net/core/dev.c:7258
 handle_softirqs+0x336/0x830 kernel/softirq.c:576
 __do_softirq kernel/softirq.c:610 [inline]
 invoke_softirq kernel/softirq.c:450 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 common_interrupt+0xb5/0xd0 arch/x86/kernel/irq.c:242
 </IRQ>
 <TASK>
 asm_common_interrupt+0x22/0x40 arch/x86/include/asm/idtentry.h:667
RIP: 0010:finish_lock_switch+0x12f/0x290 kernel/sched/core.c:4804
Code: 83 c7 18 be ff ff ff ff e8 fe cc 6a 08 85 c0 74 46 4d 85 ff 75 62 0f 1f 44 00 00 48 89 df e8 c8 3b 74 08 e8 d3 cc 2a 00 fb 5b <41> 5c 41 5d 41 5e 41 5f 5d c3 48 89 df e8 2f 0e fe ff 43 80 3c 2c
RSP: 0018:ffffc900032bf458 EFLAGS: 00000282
RAX: 2499c51175f64d00 RBX: ffff88807e36bb80 RCX: 2499c51175f64d00
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a2a40
RBP: 1ffff11017207613 R08: ffffffff901e90cf R09: 1ffffffff203d219
R10: dffffc0000000000 R11: fffffbfff203d21a R12: 1ffff110172075c1
R13: dffffc0000000000 R14: ffff8880b903ae08 R15: 0000000000000000
 finish_task_switch+0x12f/0x650 kernel/sched/core.c:4921
 context_switch kernel/sched/core.c:5052 [inline]
 __schedule+0x11cb/0x4350 kernel/sched/core.c:6395
 preempt_schedule_irq+0xbb/0x160 kernel/sched/core.c:6799
 irqentry_exit+0x63/0x70 kernel/entry/common.c:432
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:kasan_check_range+0x1b6/0x290 mm/kasan/generic.c:-1
Code: df 49 8d 5f 07 4d 85 ff 49 0f 49 df 48 83 e3 f8 49 29 df 74 0e 41 80 3b 00 75 69 49 ff c3 49 ff cf 75 f2 5b 41 5c 41 5e 41 5f <5d> c3 45 84 ff 0f 85 91 00 00 00 41 f7 c7 00 ff 00 00 0f 85 89 00
RSP: 0018:ffffc900032bf820 EFLAGS: 00000256
RAX: 1ffff11003250801 RBX: dffffc0000000000 RCX: ffffffff81c468a3
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff888019284210
RBP: 0000000000546dc0 R08: ffff888019284217 R09: 1ffff11003250842
R10: dffffc0000000000 R11: ffffed1003250843 R12: 0000001278984d8e
R13: ffff888019284228 R14: ffff888019284210 R15: 0000000000000014
 instrument_write include/linux/instrumented.h:41 [inline]
 __set_bit include/asm-generic/bitops/instrumented-non-atomic.h:27 [inline]
 __set_page_owner_handle mm/page_owner.c:166 [inline]
 __set_page_owner+0x1b3/0x2d0 mm/page_owner.c:182
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 __alloc_pages_node include/linux/gfp.h:570 [inline]
 alloc_pages_node include/linux/gfp.h:584 [inline]
 kmalloc_large_node+0x7d/0x1a0 mm/slub.c:4426
 __kmalloc_node+0x21e/0x3a0 mm/slub.c:4442
 kmalloc_node include/linux/slab.h:630 [inline]
 kvmalloc_node+0x84/0x130 mm/util.c:619
 kvmalloc include/linux/mm.h:816 [inline]
 kvzalloc include/linux/mm.h:824 [inline]
 netif_alloc_netdev_queues net/core/dev.c:10278 [inline]
 alloc_netdev_mqs+0x616/0xc40 net/core/dev.c:10965
 tun_set_iff+0x542/0xdd0 drivers/net/tun.c:2776
 __tun_chr_ioctl+0x762/0x1f30 drivers/net/tun.c:3065
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 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: 0033:0x7f083e658e59
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f083c8b1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f083e8e0fa0 RCX: 00007f083e658e59
RDX: 0000200000000200 RSI: 00000000400454ca RDI: 0000000000000008
RBP: 00007f083e6eee6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f083e8e1038 R14: 00007f083e8e0fa0 R15: 00007fffcd836978
 </TASK>

Crashes (13):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/15 04:09 linux-5.15.y c86c4726e7f0 2130f682 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/07/03 16:18 linux-5.15.y eceeec79dbc6 58bf2096 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/06/08 02:32 linux-5.15.y dc027a595035 cc095639 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/04/28 13:56 linux-5.15.y b9d57c40a767 ce741359 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/03/31 01:41 linux-5.15.y 91d48252ad4b d0af506e .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/03/04 06:20 linux-5.15.y 3330a8d33e08 4180d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/02/27 03:15 linux-5.15.y 3330a8d33e08 a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/02/11 19:24 linux-5.15.y e45d5d41c134 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/01/14 18:27 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/01/08 05:24 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2026/01/03 01:26 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2025/12/30 15:16 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
2025/11/23 13:35 linux-5.15.y cc5ec8769306 4fb8ef37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in __tun_chr_ioctl
* Struck through repros no longer work on HEAD.