syzbot

INFO: task iou-sqp-14655:14657 blocked for more than 143 seconds.
      Not tainted 5.11.0-next-20210226-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:iou-sqp-14655   state:D stack:30296 pid:14657 ppid:  8491 flags:0x00004004
Call Trace:
 context_switch kernel/sched/core.c:4324 [inline]
 __schedule+0x90c/0x21a0 kernel/sched/core.c:5075
 schedule+0xcf/0x270 kernel/sched/core.c:5154
 schedule_timeout+0x1db/0x250 kernel/time/timer.c:1868
 do_wait_for_common kernel/sched/completion.c:85 [inline]
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x168/0x270 kernel/sched/completion.c:138
 io_sq_thread+0x27d/0x1ae0 fs/io_uring.c:6717
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Showing all locks held in the system:
1 lock held by khungtaskd/1663:
 #0: ffffffff8bf741e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6327
1 lock held by in:imklog/8143:
 #0: ffff888011db85f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:961
1 lock held by syz-executor.5/14655:
 #0: ffff88814406a070 (&sqd->lock){+.+.}-{3:3}, at: io_sq_thread_park+0x5d/0x130 fs/io_uring.c:7108

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 1663 Comm: khungtaskd Not tainted 5.11.0-next-20210226-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0xfa/0x151 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:147 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:253 [inline]
 watchdog+0xd8e/0xf40 kernel/hung_task.c:338
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 24 Comm: kworker/u4:1 Not tainted 5.11.0-next-20210226-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet
RIP: 0010:__orc_find+0x11/0xf0 arch/x86/kernel/unwind_orc.c:35
Code: cc cc cc cc cc cc cc cc cc 48 8b 07 c3 66 66 2e 0f 1f 84 00 00 00 00 00 90 41 57 89 d0 41 56 41 55 41 54 4c 8d 64 87 fc 55 53 <48> 83 ec 10 85 d2 0f 84 95 00 00 00 4c 39 e7 49 89 fd 0f 87 9a 00
RSP: 0018:ffffc90000db0558 EFLAGS: 00000216
RAX: 000000000000000a RBX: 1ffff920001b60ba RCX: ffffffff81b6b7f4
RDX: 000000000000000a RSI: ffffffff8e491a54 RDI: ffffffff8dda3958
RBP: 0000000000000002 R08: ffffffff8e491a90 R09: ffffffff8e491a54
R10: 0000000000084087 R11: 000000000002a2e8 R12: ffffffff8dda397c
R13: ffffc90000db069d R14: ffffc90000db06b8 R15: ffffc90000db0668
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd53b0f2000 CR3: 0000000026133000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 orc_find arch/x86/kernel/unwind_orc.c:173 [inline]
 unwind_next_frame+0x342/0x2000 arch/x86/kernel/unwind_orc.c:443
 arch_stack_walk+0x7d/0xe0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x8c/0xc0 kernel/stacktrace.c:121
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
 ____kasan_slab_free mm/kasan/common.c:360 [inline]
 ____kasan_slab_free mm/kasan/common.c:325 [inline]
 __kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
 kasan_slab_free include/linux/kasan.h:199 [inline]
 slab_free_hook mm/slub.c:1562 [inline]
 slab_free_freelist_hook+0x72/0x1b0 mm/slub.c:1600
 slab_free mm/slub.c:3161 [inline]
 kfree+0xe5/0x7b0 mm/slub.c:4213
 skb_free_head net/core/skbuff.c:650 [inline]
 skb_release_data+0x622/0x750 net/core/skbuff.c:671
 skb_release_all net/core/skbuff.c:725 [inline]
 __kfree_skb net/core/skbuff.c:739 [inline]
 kfree_skb net/core/skbuff.c:757 [inline]
 kfree_skb+0x133/0x3f0 net/core/skbuff.c:751
 __netif_receive_skb_core+0x821/0x37f0 net/core/dev.c:5339
 __netif_receive_skb_one_core+0xae/0x180 net/core/dev.c:5363
 __netif_receive_skb+0x27/0x1c0 net/core/dev.c:5479
 process_backlog+0x232/0x6c0 net/core/dev.c:6346
 __napi_poll+0xaf/0x440 net/core/dev.c:6892
 napi_poll net/core/dev.c:6959 [inline]
 net_rx_action+0x801/0xb40 net/core/dev.c:7036
 __do_softirq+0x29b/0x9f6 kernel/softirq.c:345
 do_softirq.part.0+0xc8/0x110 kernel/softirq.c:248
 </IRQ>
 do_softirq kernel/softirq.c:240 [inline]
 __local_bh_enable_ip+0x102/0x120 kernel/softirq.c:198
 local_bh_enable include/linux/bottom_half.h:32 [inline]
 rcu_read_unlock_bh include/linux/rcupdate.h:745 [inline]
 __dev_queue_xmit+0x1b71/0x2e00 net/core/dev.c:4209
 batadv_send_skb_packet+0x4a9/0x5f0 net/batman-adv/send.c:108
 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:393 [inline]
 batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:419 [inline]
 batadv_iv_send_outstanding_bat_ogm_packet+0x781/0x920 net/batman-adv/bat_iv_ogm.c:1711
 process_one_work+0x98d/0x1600 kernel/workqueue.c:2275
 worker_thread+0x64c/0x1120 kernel/workqueue.c:2421
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294