[v6.1] INFO: rcu detected stall in batadv_iv_send_outstanding_bat_ogm_packet

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 61fd484b2cf6 Linux 6.1.38
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=15b8f2b0a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a21f730857cfa53
dashboard link: https://syzkaller.appspot.com/bug?extid=4c788c9594fddd0046ab
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/eb0882a0450c/disk-61fd484b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/483d02c4c64c/vmlinux-61fd484b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3b4bb7e6bcff/bzImage-61fd484b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4c788c...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P4262/1:b..l
(detected by 0, t=10503 jiffies, g=57189, q=107 ncpus=2)
task:kworker/u4:41 state:R running task stack:23384 pid:4262 ppid:2 flags:0x00004000
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x132c/0x4330 kernel/sched/core.c:6554
preempt_schedule_irq+0xf7/0x1c0 kernel/sched/core.c:6866
irqentry_exit+0x53/0x80 kernel/entry/common.c:433
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:203
Code: e8 25 00 00 00 0f 0b 0f 1f 00 53 48 89 fb e8 17 00 00 00 48 8b 3d a8 7a c9 0c 48 89 de 5b e9 87 94 55 00 cc cc cc cc cc cc cc <48> 8b 04 24 65 48 8b 0d f4 93 78 7e 65 8b 15 f5 93 78 7e f7 c2 00
RSP: 0018:ffffc9000ce37a50 EFLAGS: 00000293
RAX: ffffffff8a507355 RBX: 00000000000000c3 RCX: ffff88803ab89dc0
RDX: 0000000000000000 RSI: ffffffff8aebe4a0 RDI: ffffffff8b3cce60
RBP: ffffc9000ce37b98 R08: dffffc0000000000 R09: fffffbfff1ca6a76
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff88807ee1e6c0
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffff888075a40618
rcu_lock_acquire+0xa/0x30 include/linux/rcupdate.h:306
rcu_read_lock include/linux/rcupdate.h:747 [inline]
batadv_iv_ogm_slide_own_bcast_window net/batman-adv/bat_iv_ogm.c:755 [inline]
batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:826 [inline]
batadv_iv_ogm_schedule+0x425/0x1000 net/batman-adv/bat_iv_ogm.c:869
batadv_iv_send_outstanding_bat_ogm_packet+0x6fa/0x800 net/batman-adv/bat_iv_ogm.c:1713
process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2289
worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
rcu: rcu_preempt kthread starved for 10490 jiffies! g57189 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
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:26712 pid:16 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5241 [inline]
__schedule+0x132c/0x4330 kernel/sched/core.c:6554
schedule+0xbf/0x180 kernel/sched/core.c:6630
schedule_timeout+0x1b9/0x300 kernel/time/timer.c:1935
rcu_gp_fqs_loop+0x2c2/0x1010 kernel/rcu/tree.c:1661
rcu_gp_kthread+0xa3/0x3a0 kernel/rcu/tree.c:1860
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 PID: 15616 Comm: kworker/u4:48 Not tainted 6.1.38-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:check_kcov_mode kernel/kcov.c:184 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0x32/0x60 kernel/kcov.c:207
Code: f4 93 78 7e 65 8b 15 f5 93 78 7e f7 c2 00 01 ff 00 74 11 f7 c2 00 01 00 00 74 35 83 b9 1c 16 00 00 00 74 2c 8b 91 f8 15 00 00 <83> fa 02 75 21 48 8b 91 00 16 00 00 48 8b 32 48 8d 7e 01 8b 89 fc
RSP: 0018:ffffc900032cf598 EFLAGS: 00000246
RAX: ffffffff817ecd3d RBX: 1ffff11017328031 RCX: ffff888035d28000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc900032cf980 R08: ffffffff817ecd06 R09: fffffbfff2052845
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000800000000
R13: dffffc0000000000 R14: 0000000000000001 R15: ffff8880b9940188
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f34aafa4748 CR3: 000000000cc8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
</IRQ>
<TASK>
csd_lock_wait kernel/smp.c:413 [inline]
smp_call_function_many_cond+0x1f7d/0x33d0 kernel/smp.c:987
on_each_cpu_cond_mask+0x3b/0x80 kernel/smp.c:1155
on_each_cpu include/linux/smp.h:71 [inline]
text_poke_sync arch/x86/kernel/alternative.c:1316 [inline]
text_poke_bp_batch+0x2bb/0x940 arch/x86/kernel/alternative.c:1516
text_poke_flush arch/x86/kernel/alternative.c:1707 [inline]
text_poke_finish+0x16/0x30 arch/x86/kernel/alternative.c:1714
arch_jump_label_transform_apply+0x13/0x20 arch/x86/kernel/jump_label.c:146
static_key_enable_cpuslocked+0x12e/0x250 kernel/jump_label.c:177
static_key_enable+0x16/0x20 kernel/jump_label.c:190
toggle_allocation_gate+0xbf/0x480 mm/kfence/core.c:804
process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2289
worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436
kthread+0x26e/0x300 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.