Message-ID: <685ca247.a00a0220.2e5631.01be.GAE@google.com>
Date: Wed, 25 Jun 2025 18:28:39 -0700
From: syzbot <syzbot+bee5156c0b574d986bb8@...kaller.appspotmail.com>
To: davem@...emloft.net, edumazet@...gle.com, horms@...nel.org, 
	kuba@...nel.org, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [net?] INFO: rcu detected stall in linkwatch_event (5)

Hello,

syzbot found the following issue on:

HEAD commit:    3f75bfff44be Merge tag 'mtd/fixes-for-6.16-rc3' of git://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=172dfd0c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=4130f4d8a06c3e71
dashboard link: https://syzkaller.appspot.com/bug?extid=bee5156c0b574d986bb8
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=124f330c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c7c40e7590a7/disk-3f75bfff.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/72789e04c1ce/vmlinux-3f75bfff.xz
kernel image: https://storage.googleapis.com/syzbot-assets/21a0b3ad49c2/bzImage-3f75bfff.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bee5156c0b574d986bb8@...kaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	(detected by 0, t=10502 jiffies, g=8865, q=697 ncpus=2)
rcu: All QSes seen, last rcu_preempt kthread activity 10500 (4294960814-4294950314), jiffies_till_next_fqs=1, root ->qsmask 0x0
rcu: rcu_preempt kthread starved for 10500 jiffies! g8865 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:27672 pid:16    tgid:16    ppid:2      task_flags:0x208040 flags:0x00004000
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5396 [inline]
 __schedule+0x116a/0x5de0 kernel/sched/core.c:6785
 __schedule_loop kernel/sched/core.c:6863 [inline]
 schedule+0xe7/0x3a0 kernel/sched/core.c:6878
 schedule_timeout+0x123/0x290 kernel/time/sleep_timeout.c:99
 rcu_gp_fqs_loop+0x1ea/0xb00 kernel/rcu/tree.c:2054
 rcu_gp_kthread+0x270/0x380 kernel/rcu/tree.c:2256
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
rcu: Stack dump where RCU GP kthread last ran:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 3539 Comm: kworker/u8:11 Not tainted 6.16.0-rc2-syzkaller-00278-g3f75bfff44be #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_unbound linkwatch_event
RIP: 0010:its_return_thunk+0x0/0x10 arch/x86/lib/retpoline.S:412
Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc <c3> cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 e9 5b fd a8 f5 cc
RSP: 0018:ffffc90000a08df8 EFLAGS: 00000046
RAX: 0000000000000000 RBX: ffff888033695370 RCX: 0000000000000001
RDX: 0000000000000000 RSI: ffff8880b8527c98 RDI: ffff888033695370
RBP: ffff8880b8527c98 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff9b00b188 R12: ffff888033694880
R13: ffff888033695370 R14: 00000000ffffffff R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff888124853000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa82f551f98 CR3: 000000007f635000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __lock_is_held kernel/locking/lockdep.c:5604 [inline]
 lock_is_held_type+0xb0/0x150 kernel/locking/lockdep.c:5943
 lock_is_held include/linux/lockdep.h:249 [inline]
 __run_hrtimer kernel/time/hrtimer.c:1727 [inline]
 __hrtimer_run_queues+0x86a/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_interrupt+0x397/0x8e0 kernel/time/hrtimer.c:1887
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline]
 __sysvec_apic_timer_interrupt+0x108/0x3f0 arch/x86/kernel/apic/apic.c:1056
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0x9f/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0x31/0x80 kernel/locking/spinlock.c:194
Code: f5 53 48 8b 74 24 10 48 89 fb 48 83 c7 18 e8 76 c0 15 f6 48 89 df e8 5e 14 16 f6 f7 c5 00 02 00 00 75 23 9c 58 f6 c4 02 75 37 <bf> 01 00 00 00 e8 95 34 06 f6 65 8b 05 8e 1a 4a 08 85 c0 74 16 5b
RSP: 0018:ffffc9000cf57308 EFLAGS: 00000246
RAX: 0000000000000006 RBX: ffffffff9b059128 RCX: 0000000000000006
RDX: 0000000000000000 RSI: ffffffff8de19fc0 RDI: ffffffff8c157960
RBP: 0000000000000286 R08: 0000000000000001 R09: 0000000000000001
R10: ffffffff90a81557 R11: 0000000000000001 R12: dffffc0000000000
R13: 0000000000000002 R14: 0000000000000002 R15: ffff88804f378000
 __debug_check_no_obj_freed lib/debugobjects.c:1108 [inline]
 debug_check_no_obj_freed+0x31f/0x600 lib/debugobjects.c:1129
 slab_free_hook mm/slub.c:2312 [inline]
 slab_free mm/slub.c:4643 [inline]
 kfree+0x28f/0x4d0 mm/slub.c:4842
 skb_kfree_head net/core/skbuff.c:1048 [inline]
 skb_free_head+0x114/0x210 net/core/skbuff.c:1060
 pskb_expand_head+0x3c4/0x1030 net/core/skbuff.c:2273
 netlink_trim+0x22d/0x310 net/netlink/af_netlink.c:1295
 netlink_broadcast_filtered+0xca/0xf10 net/netlink/af_netlink.c:1501
 nlmsg_multicast_filtered include/net/netlink.h:1151 [inline]
 genlmsg_multicast_netns_filtered include/net/genetlink.h:495 [inline]
 genlmsg_multicast_netns include/net/genetlink.h:512 [inline]
 team_nl_send_multicast+0xef/0x170 drivers/net/team/team_core.c:2841
 team_nl_send_port_list_get+0x68a/0x750 drivers/net/team/team_core.c:2793
 team_nl_send_event_port_get drivers/net/team/team_core.c:2855 [inline]
 __team_port_change_send+0x242/0x560 drivers/net/team/team_core.c:2913
 __team_port_change_check drivers/net/team/team_core.c:2945 [inline]
 team_port_change_check drivers/net/team/team_core.c:2967 [inline]
 team_device_event+0x61b/0x770 drivers/net/team/team_core.c:2996
 notifier_call_chain+0xb9/0x410 kernel/notifier.c:85
 call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:2230
 netif_state_change+0x165/0x3b0 net/core/dev.c:1584
 linkwatch_do_dev+0x12b/0x160 net/core/link_watch.c:186
 __linkwatch_run_queue+0x2aa/0x8a0 net/core/link_watch.c:244
 linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304
 process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c2/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d4/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
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