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: 224d, last: 14h42m
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 336d 336d 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 1 42d 42d 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 193d 386d 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 69d 143d 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-....: (10436 ticks this GP) idle=9b2c/1/0x4000000000000000 softirq=13196/13230 fqs=4856
rcu: 	         hardirqs   softirqs   csw/system
rcu: 	 number:  1874182        560            0
rcu: 	cputime:    15964      36503           34   ==> 52470(ms)
rcu: 	(t=10500 jiffies g=9717 q=713 ncpus=2)
CPU: 1 PID: 5957 Comm: syz.0.25 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:lock_acquire+0x208/0x420 kernel/locking/lockdep.c:5758
Code: f7 84 24 80 00 00 00 00 02 00 00 43 c6 44 3c 04 f8 0f 85 f0 00 00 00 41 f7 c6 00 02 00 00 74 01 fb 48 c7 44 24 60 0e 36 e0 45 <4b> c7 04 3c 00 00 00 00 43 c7 44 3c 08 00 00 00 00 65 48 8b 04 25
RSP: 0018:ffffc900001f0820 EFLAGS: 00000206
RAX: 0000000000000001 RBX: 0000000000000001 RCX: 3348901293b05a00
RDX: 0000000000000000 RSI: ffffffff8acadae0 RDI: ffffffff8b1c85a0
RBP: ffffc900001f0928 R08: dffffc0000000000 R09: 1ffffffff22382a0
R10: dffffc0000000000 R11: fffffbfff22382a1 R12: 1ffff9200003e110
R13: ffffffff8d7d8740 R14: 0000000000000246 R15: dffffc0000000000
FS:  0000555593951500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000004e686 CR3: 0000000077ba7000 CR4: 00000000003506e0
Call Trace:
 <IRQ>
 debug_objects_fill_pool+0xab/0x730 lib/debugobjects.c:615
 debug_object_assert_init+0x66/0x2f0 lib/debugobjects.c:894
 debug_timer_assert_init kernel/time/timer.c:792 [inline]
 debug_assert_init kernel/time/timer.c:837 [inline]
 __mod_timer+0x55/0xdb0 kernel/time/timer.c:1020
 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 00 54 31 09 e8 9b 23 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:ffffc90003047518 EFLAGS: 00000286
RAX: 3348901293b05a00 RBX: 0000000000000000 RCX: 3348901293b05a00
RDX: dffffc0000000000 RSI: ffffffff8acac960 RDI: ffffffff8b1c85a0
RBP: ffffc90003047570 R08: ffffffff8e8aeeef R09: 1ffffffff1d15ddd
R10: dffffc0000000000 R11: fffffbfff1d15dde R12: ffff88802bac8000
R13: dffffc0000000000 R14: ffff88802150da00 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
 unwind_next_frame+0x200f/0x2970 arch/x86/kernel/unwind_orc.c:672
 arch_stack_walk+0x144/0x190 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:46
 __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+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb5e0b9c799
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:00007ffe8da6fbb8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007ffe8da6fca0 RCX: 00007fb5e0b9c799
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000004e686 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2d020000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb5e0e15fac R14: 00007fb5e0e15fa8 R15: 00007fb5e0e15fa0
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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.