syzbot

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.15.125-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.0/15246 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffffffff8c9dfa60 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:206 [inline]
ffffffff8c9dfa60 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492

and this task is already holding:
ffff88801e60c908 (&sch->q.lock){+.-.}-{2:2}, at: netem_change+0x257/0x20c0 net/sched/sch_netem.c:972
which would create a new lock dependency:
 (&sch->q.lock){+.-.}-{2:2} -> (fs_reclaim){+.+.}-{0:0}

but this new dependency connects a SOFTIRQ-irq-safe lock:
 (&sch->q.lock){+.-.}-{2:2}

... which became SOFTIRQ-irq-safe at:
  lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
  __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
  _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
  spin_lock include/linux/spinlock.h:363 [inline]
  dequeue_skb net/sched/sch_generic.c:240 [inline]
  qdisc_restart net/sched/sch_generic.c:397 [inline]
  __qdisc_run+0xc2c/0x1e90 net/sched/sch_generic.c:415
  qdisc_run+0x10d/0x320 include/net/pkt_sched.h:132
  net_tx_action+0x73a/0x8e0 net/core/dev.c:5065
  __do_softirq+0x3b3/0x93a kernel/softirq.c:558
  do_softirq+0x162/0x240 kernel/softirq.c:459
  __local_bh_enable_ip+0x1b1/0x1f0 kernel/softirq.c:383
  spin_unlock_bh include/linux/spinlock.h:408 [inline]
  lapb_device_event+0x4ae/0x630 net/lapb/lapb_iface.c:527
  notifier_call_chain kernel/notifier.c:83 [inline]
  raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:391
  __dev_notify_flags+0x304/0x610
  dev_change_flags+0xe7/0x190 net/core/dev.c:8863
  devinet_ioctl+0x92e/0x1b20 net/ipv4/devinet.c:1142
  inet_ioctl+0x32d/0x400 net/ipv4/af_inet.c:975
  sock_do_ioctl+0x11d/0x5a0 net/socket.c:1121
  sock_ioctl+0x47f/0x770 net/socket.c:1238
  vfs_ioctl fs/ioctl.c:51 [inline]
  __do_sys_ioctl fs/ioctl.c:874 [inline]
  __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
  do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x61/0xcb

to a SOFTIRQ-irq-unsafe lock:
 (fs_reclaim){+.+.}-{0:0}

... which became SOFTIRQ-irq-unsafe at:
...
  lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
  __fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
  fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4561
  might_alloc include/linux/sched/mm.h:206 [inline]
  slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492
  slab_alloc_node mm/slub.c:3134 [inline]
  slab_alloc mm/slub.c:3228 [inline]
  kmem_cache_alloc_trace+0x49/0x290 mm/slub.c:3245
  kmalloc include/linux/slab.h:591 [inline]
  kzalloc include/linux/slab.h:721 [inline]
  alloc_workqueue_attrs kernel/workqueue.c:3406 [inline]
  wq_numa_init+0x122/0x49f kernel/workqueue.c:5997
  workqueue_init+0x18/0x5e1 kernel/workqueue.c:6124
  kernel_init_freeable+0x40a/0x5c5 init/main.c:1592
  kernel_init+0x19/0x290 init/main.c:1499
  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

other info that might help us debug this:

 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               local_irq_disable();
                               lock(&sch->q.lock);
                               lock(fs_reclaim);
  <Interrupt>
    lock(&sch->q.lock);

 *** DEADLOCK ***

2 locks held by syz-executor.0/15246:
 #0: ffffffff8d9e1008 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
 #0: ffffffff8d9e1008 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x94c/0xee0 net/core/rtnetlink.c:5596
 #1: ffff88801e60c908 (&sch->q.lock){+.-.}-{2:2}, at: netem_change+0x257/0x20c0 net/sched/sch_netem.c:972

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&sch->q.lock){+.-.}-{2:2} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
                    __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
                    _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                    spin_lock_bh include/linux/spinlock.h:368 [inline]
                    dev_reset_queue+0xc1/0x140 net/sched/sch_generic.c:1245
                    netdev_for_each_tx_queue include/linux/netdevice.h:2379 [inline]
                    dev_deactivate_many+0x6ad/0xbf0 net/sched/sch_generic.c:1313
                    dev_deactivate+0x177/0x270 net/sched/sch_generic.c:1336
                    linkwatch_do_dev+0x104/0x160 net/core/link_watch.c:165
                    __linkwatch_run_queue+0x4ca/0x7f0 net/core/link_watch.c:213
                    linkwatch_event+0x48/0x50 net/core/link_watch.c:252
                    process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
                    worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
                    kthread+0x3f6/0x4f0 kernel/kthread.c:319
                    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
   IN-SOFTIRQ-W at:
                    lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
                    __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
                    _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
                    spin_lock include/linux/spinlock.h:363 [inline]
                    dequeue_skb net/sched/sch_generic.c:240 [inline]
                    qdisc_restart net/sched/sch_generic.c:397 [inline]
                    __qdisc_run+0xc2c/0x1e90 net/sched/sch_generic.c:415
                    qdisc_run+0x10d/0x320 include/net/pkt_sched.h:132
                    net_tx_action+0x73a/0x8e0 net/core/dev.c:5065
                    __do_softirq+0x3b3/0x93a kernel/softirq.c:558
                    do_softirq+0x162/0x240 kernel/softirq.c:459
                    __local_bh_enable_ip+0x1b1/0x1f0 kernel/softirq.c:383
                    spin_unlock_bh include/linux/spinlock.h:408 [inline]
                    lapb_device_event+0x4ae/0x630 net/lapb/lapb_iface.c:527
                    notifier_call_chain kernel/notifier.c:83 [inline]
                    raw_notifier_call_chain+0xd0/0x170 kernel/notifier.c:391
                    __dev_notify_flags+0x304/0x610
                    dev_change_flags+0xe7/0x190 net/core/dev.c:8863
                    devinet_ioctl+0x92e/0x1b20 net/ipv4/devinet.c:1142
                    inet_ioctl+0x32d/0x400 net/ipv4/af_inet.c:975
                    sock_do_ioctl+0x11d/0x5a0 net/socket.c:1121
                    sock_ioctl+0x47f/0x770 net/socket.c:1238
                    vfs_ioctl fs/ioctl.c:51 [inline]
                    __do_sys_ioctl fs/ioctl.c:874 [inline]
                    __se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
                    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
                    do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
                    entry_SYSCALL_64_after_hwframe+0x61/0xcb
   INITIAL USE at:
                   lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
                   __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
                   _raw_spin_lock_bh+0x31/0x40 kernel/locking/spinlock.c:178
                   spin_lock_bh include/linux/spinlock.h:368 [inline]
                   dev_reset_queue+0xc1/0x140 net/sched/sch_generic.c:1245
                   netdev_for_each_tx_queue include/linux/netdevice.h:2379 [inline]
                   dev_deactivate_many+0x6ad/0xbf0 net/sched/sch_generic.c:1313
                   dev_deactivate+0x177/0x270 net/sched/sch_generic.c:1336
                   linkwatch_do_dev+0x104/0x160 net/core/link_watch.c:165
                   __linkwatch_run_queue+0x4ca/0x7f0 net/core/link_watch.c:213
                   linkwatch_event+0x48/0x50 net/core/link_watch.c:252
                   process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310
                   worker_thread+0xaca/0x1280 kernel/workqueue.c:2457
                   kthread+0x3f6/0x4f0 kernel/kthread.c:319
                   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 }
 ... key      at: [<ffffffff91799380>] qdisc_alloc.__key+0x0/0x20

the dependencies between the lock to be acquired
 and SOFTIRQ-irq-unsafe lock:
-> (fs_reclaim){+.+.}-{0:0} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
                    __fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
                    fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4561
                    might_alloc include/linux/sched/mm.h:206 [inline]
                    slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492
                    slab_alloc_node mm/slub.c:3134 [inline]
                    slab_alloc mm/slub.c:3228 [inline]
                    kmem_cache_alloc_trace+0x49/0x290 mm/slub.c:3245
                    kmalloc include/linux/slab.h:591 [inline]
                    kzalloc include/linux/slab.h:721 [inline]
                    alloc_workqueue_attrs kernel/workqueue.c:3406 [inline]
                    wq_numa_init+0x122/0x49f kernel/workqueue.c:5997
                    workqueue_init+0x18/0x5e1 kernel/workqueue.c:6124
                    kernel_init_freeable+0x40a/0x5c5 init/main.c:1592
                    kernel_init+0x19/0x290 init/main.c:1499
                    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
   SOFTIRQ-ON-W at:
                    lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
                    __fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
                    fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4561
                    might_alloc include/linux/sched/mm.h:206 [inline]
                    slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492
                    slab_alloc_node mm/slub.c:3134 [inline]
                    slab_alloc mm/slub.c:3228 [inline]
                    kmem_cache_alloc_trace+0x49/0x290 mm/slub.c:3245
                    kmalloc include/linux/slab.h:591 [inline]
                    kzalloc include/linux/slab.h:721 [inline]
                    alloc_workqueue_attrs kernel/workqueue.c:3406 [inline]
                    wq_numa_init+0x122/0x49f kernel/workqueue.c:5997
                    workqueue_init+0x18/0x5e1 kernel/workqueue.c:6124
                    kernel_init_freeable+0x40a/0x5c5 init/main.c:1592
                    kernel_init+0x19/0x290 init/main.c:1499
                    ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
   INITIAL USE at:
                   lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
                   __fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
                   fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4561
                   might_alloc include/linux/sched/mm.h:206 [inline]
                   slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492
                   slab_alloc_node mm/slub.c:3134 [inline]
                   slab_alloc mm/slub.c:3228 [inline]
                   kmem_cache_alloc_trace+0x49/0x290 mm/slub.c:3245
                   kmalloc include/linux/slab.h:591 [inline]
                   kzalloc include/linux/slab.h:721 [inline]
                   alloc_workqueue_attrs kernel/workqueue.c:3406 [inline]
                   wq_numa_init+0x122/0x49f kernel/workqueue.c:5997
                   workqueue_init+0x18/0x5e1 kernel/workqueue.c:6124
                   kernel_init_freeable+0x40a/0x5c5 init/main.c:1592
                   kernel_init+0x19/0x290 init/main.c:1499
                   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 }
 ... key      at: [<ffffffff8c9dfa60>] __fs_reclaim_map+0x0/0x160
 ... acquired at:
   lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
   __fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
   fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4561
   might_alloc include/linux/sched/mm.h:206 [inline]
   slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492
   slab_alloc_node mm/slub.c:3134 [inline]
   __kmalloc_node+0x71/0x390 mm/slub.c:4451
   kmalloc_node include/linux/slab.h:614 [inline]
   kvmalloc_node+0x80/0x140 mm/util.c:619
   kvmalloc include/linux/mm.h:805 [inline]
   get_dist_table+0x83/0x2c0 net/sched/sch_netem.c:788
   netem_change+0xa05/0x20c0 net/sched/sch_netem.c:988
   netem_init+0x58/0xb0 net/sched/sch_netem.c:1075
   qdisc_create+0x8ae/0x1390 net/sched/sch_api.c:1264
   tc_modify_qdisc+0xac5/0x1710
   rtnetlink_rcv_msg+0x993/0xee0 net/core/rtnetlink.c:5599
   netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2505
   netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
   netlink_unicast+0x7b6/0x980 net/netlink/af_netlink.c:1356
   netlink_sendmsg+0xa30/0xd60 net/netlink/af_netlink.c:1924
   sock_sendmsg_nosec net/socket.c:704 [inline]
   sock_sendmsg net/socket.c:724 [inline]
   ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
   ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
   __sys_sendmsg net/socket.c:2495 [inline]
   __do_sys_sendmsg net/socket.c:2504 [inline]
   __se_sys_sendmsg+0x19a/0x260 net/socket.c:2502
   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
   do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
   entry_SYSCALL_64_after_hwframe+0x61/0xcb


stack backtrace:
CPU: 1 PID: 15246 Comm: syz-executor.0 Not tainted 5.15.125-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_bad_irq_dependency kernel/locking/lockdep.c:2567 [inline]
 check_irq_usage kernel/locking/lockdep.c:2806 [inline]
 check_prev_add kernel/locking/lockdep.c:3057 [inline]
 check_prevs_add kernel/locking/lockdep.c:3172 [inline]
 validate_chain+0x4cfe/0x58b0 kernel/locking/lockdep.c:3787
 __lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5011
 lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5622
 __fs_reclaim_acquire mm/page_alloc.c:4547 [inline]
 fs_reclaim_acquire+0x83/0x120 mm/page_alloc.c:4561
 might_alloc include/linux/sched/mm.h:206 [inline]
 slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492
 slab_alloc_node mm/slub.c:3134 [inline]
 __kmalloc_node+0x71/0x390 mm/slub.c:4451
 kmalloc_node include/linux/slab.h:614 [inline]
 kvmalloc_node+0x80/0x140 mm/util.c:619
 kvmalloc include/linux/mm.h:805 [inline]
 get_dist_table+0x83/0x2c0 net/sched/sch_netem.c:788
 netem_change+0xa05/0x20c0 net/sched/sch_netem.c:988
 netem_init+0x58/0xb0 net/sched/sch_netem.c:1075
 qdisc_create+0x8ae/0x1390 net/sched/sch_api.c:1264
 tc_modify_qdisc+0xac5/0x1710
 rtnetlink_rcv_msg+0x993/0xee0 net/core/rtnetlink.c:5599
 netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2505
 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
 netlink_unicast+0x7b6/0x980 net/netlink/af_netlink.c:1356
 netlink_sendmsg+0xa30/0xd60 net/netlink/af_netlink.c:1924
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
 __sys_sendmsg net/socket.c:2495 [inline]
 __do_sys_sendmsg net/socket.c:2504 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2502
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f3f38dc6ae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3f373270c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3f38ee6050 RCX: 00007f3f38dc6ae9
RDX: 0000000000000000 RSI: 0000000020000440 RDI: 0000000000000003
RBP: 00007f3f38e1247a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f3f38ee6050 R15: 00007fffe3c8cda8
 </TASK>
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:209
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 15246, name: syz-executor.0
INFO: lockdep is turned off.
Preemption disabled at:
[<0000000000000000>] 0x0
CPU: 1 PID: 15246 Comm: syz-executor.0 Not tainted 5.15.125-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 ___might_sleep+0x547/0x6a0 kernel/sched/core.c:9625
 might_alloc include/linux/sched/mm.h:209 [inline]
 slab_pre_alloc_hook+0x44/0xc0 mm/slab.h:492
 slab_alloc_node mm/slub.c:3134 [inline]
 __kmalloc_node+0x71/0x390 mm/slub.c:4451
 kmalloc_node include/linux/slab.h:614 [inline]
 kvmalloc_node+0x80/0x140 mm/util.c:619
 kvmalloc include/linux/mm.h:805 [inline]
 get_dist_table+0x83/0x2c0 net/sched/sch_netem.c:788
 netem_change+0xa05/0x20c0 net/sched/sch_netem.c:988
 netem_init+0x58/0xb0 net/sched/sch_netem.c:1075
 qdisc_create+0x8ae/0x1390 net/sched/sch_api.c:1264
 tc_modify_qdisc+0xac5/0x1710
 rtnetlink_rcv_msg+0x993/0xee0 net/core/rtnetlink.c:5599
 netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2505
 netlink_unicast_kernel net/netlink/af_netlink.c:1330 [inline]
 netlink_unicast+0x7b6/0x980 net/netlink/af_netlink.c:1356
 netlink_sendmsg+0xa30/0xd60 net/netlink/af_netlink.c:1924
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2412
 ___sys_sendmsg+0x252/0x2e0 net/socket.c:2466
 __sys_sendmsg net/socket.c:2495 [inline]
 __do_sys_sendmsg net/socket.c:2504 [inline]
 __se_sys_sendmsg+0x19a/0x260 net/socket.c:2502
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f3f38dc6ae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3f373270c8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f3f38ee6050 RCX: 00007f3f38dc6ae9
RDX: 0000000000000000 RSI: 0000000020000440 RDI: 0000000000000003
RBP: 00007f3f38e1247a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f3f38ee6050 R15: 00007fffe3c8cda8
 </TASK>