INFO: rcu detected stall in free_work (3)

Status: upstream: reported on 2026/09/29 09:30
Reported-by: syzbot+c5a56e2967a10bfd6c3d@syzkaller.appspotmail.com
First crash: 2d10h, last: 2d10h
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: rcu detected stall in free_work kvm 1 1 2104d 2104d 0/29 auto-closed as invalid on 2021/03/27 03:09
linux-5.15 INFO: rcu detected stall in free_work (2) 1 1 143d 143d 0/3 auto-obsoleted due to no activity on 2026/08/18 19:55
linux-5.15 INFO: rcu detected stall in free_work 1 1 377d 377d 0/3 auto-obsoleted due to no activity on 2025/12/27 20:01
android-5-15 BUG: soft lockup in free_work 1 1 891d 891d 0/2 auto-obsoleted due to no activity on 2024/07/22 06:27
android-5-15 BUG: soft lockup in free_work (2) 1 1 760d 760d 0/2 auto-obsoleted due to no activity on 2024/11/29 23:12

Sample crash report:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-....: (1 GPs behind) idle=981/1/0x4000000000000002 softirq=12195/12196 fqs=5235 
	(detected by 1, t=10502 jiffies, g=14441, q=4242)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 1107 Comm: kworker/0:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026
Workqueue: events free_work
RIP: 0010:pvclock_clocksource_read+0xa2/0x770 arch/x86/kernel/pvclock.c:68
Code: 48 89 f0 48 c1 e8 03 48 89 44 24 70 4c 89 d0 48 c1 e8 03 48 89 44 24 68 49 8d 4a 07 48 89 4c 24 40 48 c1 e9 03 48 89 4c 24 60 <48> 8d 4f 1d 48 89 4c 24 30 48 c1 e9 03 48 89 4c 24 58 49 bc 00 00
RSP: 0018:ffffc900000076f0 EFLAGS: 00000803
RAX: 1ffffffff1e20c02 RBX: 1ffffffff1e20c00 RCX: 1ffffffff1e20c02
RDX: 1ffffffff1e20c00 RSI: ffffffff8f10601c RDI: ffffffff8f106000
RBP: 0000000000000000 R08: ffffffff8f106008 R09: ffffffff8f106018
R10: ffffffff8f106010 R11: ffffffff8f106003 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff888021133b80 R15: ffffffff8be3f820
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc31f65e18 CR3: 000000000c08e000 CR4: 00000000003506f0
DR0: 0000200000000300 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
 <IRQ>
 kvm_clock_read arch/x86/kernel/kvmclock.c:79 [inline]
 kvm_sched_clock_read+0x14/0x40 arch/x86/kernel/kvmclock.c:91
 sched_clock_cpu+0x15/0x3c0 kernel/sched/clock.c:371
 irqtime_account_irq+0x6a/0x1b0 kernel/sched/cputime.c:61
 account_hardirq_exit include/linux/vtime.h:165 [inline]
 __irq_exit_rcu+0x99/0x230 kernel/softirq.c:656
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
 instr_sysvec_irq_work arch/x86/kernel/irq_work.c:17 [inline]
 sysvec_irq_work+0x4f/0xc0 arch/x86/kernel/irq_work.c:17
 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 42 0b 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:ffffc900000079c0 EFLAGS: 00000206
RAX: bf238cf0d9987100 RBX: 1ffff92000000f3c RCX: bf238cf0d9987100
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a48c0
RBP: ffffc90000007aa0 R08: ffffffff901f11bf R09: 1ffffffff203e237
R10: dffffc0000000000 R11: fffffbfff203e238 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]
 hsr_announce+0x29a/0x310 net/hsr/hsr_device.c:409
 call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
 expire_timers kernel/time/timer.c:1699 [inline]
 __run_timers+0x56c/0x810 kernel/time/timer.c:1970
 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
 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
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 3f b1 87 f7 65 8b 05 70 c7 37 76 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90004dbf940 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a06 RCX: bf238cf0d9987100
RDX: dffffc0000000000 RSI: ffffffff8a2b2be0 RDI: 0000000000000001
RBP: ffffc90004dbf9c0 R08: ffffffff901f10ef R09: 1ffffffff203e21d
R10: dffffc0000000000 R11: fffffbfff203e21e R12: dffffc0000000000
R13: ffff88805f7b3000 R14: ffffffff9657daa8 R15: 1ffff920009b7f28
 __debug_check_no_obj_freed lib/debugobjects.c:999 [inline]
 debug_check_no_obj_freed+0x471/0x520 lib/debugobjects.c:1020
 free_pages_prepare mm/page_alloc.c:1345 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x237/0x6c0 mm/page_alloc.c:3317
 free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
 __vunmap+0x8e0/0xa80 mm/vmalloc.c:2628
 free_work+0x56/0x80 mm/vmalloc.c:95
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/29 09:29 linux-5.15.y 0248c33e835e 7bf4ea23 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf INFO: rcu detected stall in free_work
* Struck through repros no longer work on HEAD.