syzbot


INFO: rcu detected stall in sys_close_range

Status: upstream: reported C repro on 2025/08/13 16:29
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+793af646fd66df0b254e@syzkaller.appspotmail.com
First crash: 289d, last: 3d09h
Bug presence (2)
Date Name Commit Repro Result
2025/12/22 linux-6.6.y (ToT) 5fa4793a2d2d C [report] INFO: rcu detected stall in smp_call_function
2025/12/22 upstream (ToT) 9448598b22c5 C Didn't crash
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in close_range fs 1 1 402d 402d 0/29 auto-obsoleted due to no activity on 2025/07/22 12:43
linux-6.1 INFO: rcu detected stall in sys_close_range (2) origin:lts-only 1 C error 3 35d 108d 0/3 upstream: reported C repro on 2026/02/10 20:38
linux-6.1 INFO: rcu detected stall in sys_close_range 1 C done 3 259d 452d 0/3 auto-obsoleted due to no activity on 2025/12/22 06:21
linux-5.15 INFO: rcu detected stall in sys_close_range origin:lts-only 1 syz error 3 135d 209d 0/3 upstream: reported syz repro on 2025/11/02 13:19
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2026/01/04 23:24 2h33m fix candidate upstream OK (0) job log
2025/11/19 15:50 2h26m (2) fix candidate upstream OK (0) job log

Sample crash report:
rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10173 ticks this GP) idle=090c/1/0x4000000000000000 softirq=12547/12547 fqs=4594
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1523879          0            0
rcu: 	cputime:    15784      36705           43   ==> 52490(ms)
rcu: 	(t=10500 jiffies g=11929 q=761 ncpus=2)
CPU: 1 PID: 5933 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:rcu_read_unlock_special+0x83/0x4d0 kernel/rcu/tree_plugin.h:763
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 0e fd 91 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:ffffc900001effe0 EFLAGS: 00000206
RAX: 1acee3ad49aa1c00 RBX: 1ffff9200003e000 RCX: 1acee3ad49aa1c00
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9a20
RBP: ffffc900001f00a8 R08: ffffffff911c95c7 R09: 1ffffffff22392b8
R10: dffffc0000000000 R11: fffffbfff22392b9 R12: ffffffff8d137300
R13: dffffc0000000000 R14: ffff8880b8f3cf50 R15: 1ffff110171e79ea
FS:  000055558440e500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000001c0fa CR3: 0000000076263000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 __rcu_read_unlock+0x7c/0xd0 kernel/rcu/tree_plugin.h:426
 rcu_read_unlock include/linux/rcupdate.h:818 [inline]
 is_bpf_text_address+0x27e/0x2a0 kernel/bpf/core.c:743
 kernel_text_address+0xa0/0xd0 kernel/extable.c:125
 __kernel_text_address+0xd/0x30 kernel/extable.c:79
 unwind_get_return_address+0x5d/0xc0 arch/x86/kernel/unwind_orc.c:369
 arch_stack_walk+0x11d/0x190 arch/x86/kernel/stacktrace.c:26
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1a0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1e0 mm/slub.c:3843
 skb_kfree_head net/core/skbuff.c:946 [inline]
 skb_free_head net/core/skbuff.c:958 [inline]
 skb_release_data+0x5dc/0x7b0 net/core/skbuff.c:988
 skb_release_all net/core/skbuff.c:1054 [inline]
 __kfree_skb net/core/skbuff.c:1068 [inline]
 consume_skb+0xb2/0x110 net/core/skbuff.c:1284
 ifb_xmit+0x1df/0x5b0 drivers/net/ifb.c:346
 __netdev_start_xmit include/linux/netdevice.h:4943 [inline]
 netdev_start_xmit include/linux/netdevice.h:4957 [inline]
 xmit_one net/core/dev.c:3644 [inline]
 dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3660
 sch_direct_xmit+0x25e/0x4c0 net/sched/sch_generic.c:345
 __dev_xmit_skb net/core/dev.c:3881 [inline]
 __dev_queue_xmit+0x165d/0x3660 net/core/dev.c:4416
 lapb_data_transmit+0x8a/0xa0 net/lapb/lapb_iface.c:447
 lapb_transmit_buffer+0x163/0x200 net/lapb/lapb_out.c:149
 lapb_t1timer_expiry+0x699/0xab0 net/lapb/lapb_timer.c:-1
 call_timer_fn+0x189/0x540 kernel/time/timer.c:1701
 expire_timers kernel/time/timer.c:1752 [inline]
 __run_timers+0x542/0x800 kernel/time/timer.c:2023
 run_timer_softirq+0x67/0xf0 kernel/time/timer.c:2036
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 __do_softirq kernel/softirq.c:612 [inline]
 invoke_softirq kernel/softirq.c:452 [inline]
 __irq_exit_rcu+0xd3/0x190 kernel/softirq.c:661
 irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x26a/0x8f0 kernel/sched/core.c:5255
Code: 0f 84 33 01 00 00 48 85 db 0f 85 52 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 20 84 33 09 e8 3b 2e 30 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc900033d7618 EFLAGS: 00000286
RAX: 1acee3ad49aa1c00 RBX: 0000000000000000 RCX: 1acee3ad49aa1c00
RDX: dffffc0000000000 RSI: ffffffff8acacbe0 RDI: ffffffff8b1c9a20
RBP: ffffc900033d7670 R08: ffffffff8e8b3aef R09: 1ffffffff1d1675d
R10: dffffc0000000000 R11: fffffbfff1d1675e R12: ffff888079711e00
R13: dffffc0000000000 R14: ffff88801ca7da00 R15: ffff8880b8f3cac8
 context_switch kernel/sched/core.c:5384 [inline]
 __schedule+0x155b/0x45a0 kernel/sched/core.c:6700
 preempt_schedule_common+0x82/0xc0 kernel/sched/core.c:6867
 preempt_schedule+0xc0/0xd0 kernel/sched/core.c:6891
 preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk_64.S:45
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x111/0x120 kernel/locking/spinlock.c:194
 __stack_depot_save+0x560/0x630 lib/stackdepot.c:439
 kasan_save_stack+0x4d/0x60 mm/kasan/common.c:47
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 task_work_add+0xd9/0x470 kernel/task_work.c:82
 fput+0xdd/0x1a0 fs/file_table.c:440
 filp_close+0x10f/0x150 fs/open.c:1547
 __range_close fs/file.c:698 [inline]
 __close_range+0x368/0x660 fs/file.c:755
 __do_sys_close_range fs/open.c:1599 [inline]
 __se_sys_close_range fs/open.c:1596 [inline]
 __x64_sys_close_range+0x7a/0x90 fs/open.c:1596
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6766f9ce59
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:00007ffe0f26fb58 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007ffe0f26fc40 RCX: 00007f6766f9ce59
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000001c0fa R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2c420000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6767215fac R14: 00007f6767215fa8 R15: 00007f6767215fa0
 </TASK>

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/27 06:44 linux-6.6.y 0a40c6fbd105 2b01f00e .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
2026/05/01 14:16 linux-6.6.y 258cf62a6dfd 753c55b9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
2026/04/07 05:23 linux-6.6.y 80de0a958133 4440e7c2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
2026/03/25 02:17 linux-6.6.y 4fc00fe35d46 74e70d19 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
2026/02/05 06:43 linux-6.6.y 2cf6f68313dc ea10c935 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
2025/12/22 09:05 linux-6.6.y 5fa4793a2d2d d6526ea3 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
2025/08/13 16:29 linux-6.6.y 3a8ababb8b6a 22ec1469 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan-perf INFO: rcu detected stall in sys_close_range
* Struck through repros no longer work on HEAD.