[v6.1] possible deadlock in __qdisc_run

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a1c449d00ff8 Linux 6.1.36
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=136b9dbf280000
kernel config: https://syzkaller.appspot.com/x/.config?x=88fba5343539f90e
dashboard link: https://syzkaller.appspot.com/bug?extid=85b76d35a1b5bc4c871a
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/46c419b02b39/disk-a1c449d0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cc8fc6c3c06c/vmlinux-a1c449d0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7ed5c1022bfe/Image-a1c449d0.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+85b76d...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
6.1.36-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.5/7750 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:271 [inline]
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slab.h:710 [inline]
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3318 [inline]
ffff80001585bd40 (fs_reclaim){+.+.}-{0:0}, at: __kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437

and this task is already holding:
ffff0000de631108 (&sch->q.lock){+.-.}-{2:2}, at: sch_tree_lock+0x120/0x1d4
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+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
dequeue_skb net/sched/sch_generic.c:240 [inline]
qdisc_restart net/sched/sch_generic.c:397 [inline]
__qdisc_run+0x9cc/0x239c net/sched/sch_generic.c:415
qdisc_run+0xc4/0x23c include/net/pkt_sched.h:126
net_tx_action+0x748/0x94c net/core/dev.c:5093
__do_softirq+0x30c/0xea0 kernel/softirq.c:571
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:79
call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:889
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:84
do_softirq+0x120/0x20c kernel/softirq.c:472
__local_bh_enable_ip+0x2c0/0x4d0 kernel/softirq.c:396
local_bh_enable+0x28/0x1d0 include/linux/bottom_half.h:33
rcu_read_unlock_bh include/linux/rcupdate.h:817 [inline]
ip_finish_output2+0xd40/0x11b4 net/ipv4/ip_output.c:229
__ip_finish_output+0x1b0/0x458
ip_finish_output+0x40/0x268 net/ipv4/ip_output.c:316
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip_output+0x330/0x49c net/ipv4/ip_output.c:430
dst_output include/net/dst.h:444 [inline]
ip_local_out net/ipv4/ip_output.c:126 [inline]
__ip_queue_xmit+0xe8c/0x1a00 net/ipv4/ip_output.c:532
ip_queue_xmit+0x5c/0x78 net/ipv4/ip_output.c:546
__tcp_transmit_skb+0x1938/0x31fc net/ipv4/tcp_output.c:1402
tcp_transmit_skb net/ipv4/tcp_output.c:1420 [inline]
tcp_write_xmit+0x131c/0x4e2c net/ipv4/tcp_output.c:2696
__tcp_push_pending_frames+0x98/0x228 net/ipv4/tcp_output.c:2880
tcp_push+0x448/0x688 net/ipv4/tcp.c:732
tcp_sendmsg_locked+0x2ca8/0x34f8 net/ipv4/tcp.c:1458
tcp_sendmsg+0x40/0x64 net/ipv4/tcp.c:1486
inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:830
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
sock_write_iter+0x2d8/0x414 net/socket.c:1113
call_write_iter include/linux/fs.h:2205 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x610/0x914 fs/read_write.c:584
ksys_write+0x15c/0x26c fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581

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

... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860

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.5/7750:
#0: ffff800017b8e848 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
#0: ffff800017b8e848 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x6e8/0xd94 net/core/rtnetlink.c:6094
#1: ffff0000de631108 (&sch->q.lock){+.-.}-{2:2}, at: sch_tree_lock+0x120/0x1d4

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&sch->q.lock){+.-.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x54/0x6c kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:355 [inline]
dev_reset_queue+0x130/0x1fc net/sched/sch_generic.c:1291
netdev_for_each_tx_queue include/linux/netdevice.h:2453 [inline]
dev_deactivate_many+0x540/0xa8c net/sched/sch_generic.c:1359
dev_deactivate+0x13c/0x1fc net/sched/sch_generic.c:1382
linkwatch_do_dev+0x29c/0x3a4 net/core/link_watch.c:166
__linkwatch_run_queue+0x3a0/0x700 net/core/link_watch.c:221
linkwatch_event+0x58/0x68 net/core/link_watch.c:264
process_one_work+0x7ac/0x1404 kernel/workqueue.c:2289
worker_thread+0x8e4/0xfec kernel/workqueue.c:2436
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
IN-SOFTIRQ-W at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
dequeue_skb net/sched/sch_generic.c:240 [inline]
qdisc_restart net/sched/sch_generic.c:397 [inline]
__qdisc_run+0x9cc/0x239c net/sched/sch_generic.c:415
qdisc_run+0xc4/0x23c include/net/pkt_sched.h:126
net_tx_action+0x748/0x94c net/core/dev.c:5093
__do_softirq+0x30c/0xea0 kernel/softirq.c:571
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:79
call_on_irq_stack+0x24/0x4c arch/arm64/kernel/entry.S:889
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:84
do_softirq+0x120/0x20c kernel/softirq.c:472
__local_bh_enable_ip+0x2c0/0x4d0 kernel/softirq.c:396
local_bh_enable+0x28/0x1d0 include/linux/bottom_half.h:33
rcu_read_unlock_bh include/linux/rcupdate.h:817 [inline]
ip_finish_output2+0xd40/0x11b4 net/ipv4/ip_output.c:229
__ip_finish_output+0x1b0/0x458
ip_finish_output+0x40/0x268 net/ipv4/ip_output.c:316
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip_output+0x330/0x49c net/ipv4/ip_output.c:430
dst_output include/net/dst.h:444 [inline]
ip_local_out net/ipv4/ip_output.c:126 [inline]
__ip_queue_xmit+0xe8c/0x1a00 net/ipv4/ip_output.c:532
ip_queue_xmit+0x5c/0x78 net/ipv4/ip_output.c:546
__tcp_transmit_skb+0x1938/0x31fc net/ipv4/tcp_output.c:1402
tcp_transmit_skb net/ipv4/tcp_output.c:1420 [inline]
tcp_write_xmit+0x131c/0x4e2c net/ipv4/tcp_output.c:2696
__tcp_push_pending_frames+0x98/0x228 net/ipv4/tcp_output.c:2880
tcp_push+0x448/0x688 net/ipv4/tcp.c:732
tcp_sendmsg_locked+0x2ca8/0x34f8 net/ipv4/tcp.c:1458
tcp_sendmsg+0x40/0x64 net/ipv4/tcp.c:1486
inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:830
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
sock_write_iter+0x2d8/0x414 net/socket.c:1113
call_write_iter include/linux/fs.h:2205 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x610/0x914 fs/read_write.c:584
ksys_write+0x15c/0x26c fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:646
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
INITIAL USE at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
_raw_spin_lock_bh+0x54/0x6c kernel/locking/spinlock.c:178
spin_lock_bh include/linux/spinlock.h:355 [inline]
dev_reset_queue+0x130/0x1fc net/sched/sch_generic.c:1291
netdev_for_each_tx_queue include/linux/netdevice.h:2453 [inline]
dev_deactivate_many+0x540/0xa8c net/sched/sch_generic.c:1359
dev_deactivate+0x13c/0x1fc net/sched/sch_generic.c:1382
linkwatch_do_dev+0x29c/0x3a4 net/core/link_watch.c:166
__linkwatch_run_queue+0x3a0/0x700 net/core/link_watch.c:221
linkwatch_event+0x58/0x68 net/core/link_watch.c:264
process_one_work+0x7ac/0x1404 kernel/workqueue.c:2289
worker_thread+0x8e4/0xfec kernel/workqueue.c:2436
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
}
... key at: [<ffff800019a3eae0>] 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+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
SOFTIRQ-ON-W at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
INITIAL USE at:
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
kmalloc_node_trace+0x44/0x90 mm/slab_common.c:1058
kmalloc_node include/linux/slab.h:575 [inline]
kzalloc_node include/linux/slab.h:700 [inline]
alloc_worker kernel/workqueue.c:1840 [inline]
init_rescuer+0xa4/0x264 kernel/workqueue.c:4269
workqueue_init+0x298/0x5b4 kernel/workqueue.c:6098
kernel_init_freeable+0x33c/0x528 init/main.c:1614
kernel_init+0x24/0x29c init/main.c:1519
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860
}
... key at: [<ffff80001585bd40>] __fs_reclaim_map+0x0/0xe0
... acquired at:
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xcc/0x1d0 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x84/0x1e4 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0xa0/0x354 net/sched/sch_netem.c:788
netem_change+0x754/0x1900 net/sched/sch_netem.c:985
netem_init+0x54/0xb8 net/sched/sch_netem.c:1072
qdisc_create+0x70c/0xe64 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9f0/0x1840
rtnetlink_rcv_msg+0x72c/0xd94 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2524
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6115
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1354
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1902
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x558/0x844 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x26c/0x33c net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581


stack backtrace:
CPU: 1 PID: 7750 Comm: syz-executor.5 Not tainted 6.1.36-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
__lock_acquire+0x6310/0x764c kernel/locking/lockdep.c:5056
lock_acquire+0x26c/0x7cc kernel/locking/lockdep.c:5669
__fs_reclaim_acquire mm/page_alloc.c:4683 [inline]
fs_reclaim_acquire+0x90/0x12c mm/page_alloc.c:4697
might_alloc include/linux/sched/mm.h:271 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x58/0x388 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xcc/0x1d0 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x84/0x1e4 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0xa0/0x354 net/sched/sch_netem.c:788
netem_change+0x754/0x1900 net/sched/sch_netem.c:985
netem_init+0x54/0xb8 net/sched/sch_netem.c:1072
qdisc_create+0x70c/0xe64 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9f0/0x1840
rtnetlink_rcv_msg+0x72c/0xd94 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2524
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6115
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1354
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1902
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x558/0x844 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x26c/0x33c net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:274
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 7750, name: syz-executor.5
preempt_count: 201, expected: 0
RCU nest depth: 0, expected: 0
INFO: lockdep is turned off.
Preemption disabled at:
[<ffff8000106bed08>] sch_tree_lock+0x120/0x1d4
CPU: 1 PID: 7750 Comm: syz-executor.5 Not tainted 6.1.36-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
dump_stack+0x1c/0x58 lib/dump_stack.c:113
__might_resched+0x37c/0x4d8 kernel/sched/core.c:9941
__might_sleep+0x90/0xe4 kernel/sched/core.c:9870
might_alloc include/linux/sched/mm.h:274 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slub.c:3318 [inline]
__kmem_cache_alloc_node+0x74/0x388 mm/slub.c:3437
__do_kmalloc_node mm/slab_common.c:954 [inline]
__kmalloc_node+0xcc/0x1d0 mm/slab_common.c:962
kmalloc_node include/linux/slab.h:579 [inline]
kvmalloc_node+0x84/0x1e4 mm/util.c:581
kvmalloc include/linux/slab.h:706 [inline]
get_dist_table+0xa0/0x354 net/sched/sch_netem.c:788
netem_change+0x754/0x1900 net/sched/sch_netem.c:985
netem_init+0x54/0xb8 net/sched/sch_netem.c:1072
qdisc_create+0x70c/0xe64 net/sched/sch_api.c:1314
tc_modify_qdisc+0x9f0/0x1840
rtnetlink_rcv_msg+0x72c/0xd94 net/core/rtnetlink.c:6097
netlink_rcv_skb+0x20c/0x3b8 net/netlink/af_netlink.c:2524
rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6115
netlink_unicast_kernel net/netlink/af_netlink.c:1328 [inline]
netlink_unicast+0x660/0x8d4 net/netlink/af_netlink.c:1354
netlink_sendmsg+0x834/0xb18 net/netlink/af_netlink.c:1902
sock_sendmsg_nosec net/socket.c:716 [inline]
sock_sendmsg net/socket.c:736 [inline]
____sys_sendmsg+0x558/0x844 net/socket.c:2482
___sys_sendmsg net/socket.c:2536 [inline]
__sys_sendmsg+0x26c/0x33c net/socket.c:2565
__do_sys_sendmsg net/socket.c:2574 [inline]
__se_sys_sendmsg net/socket.c:2572 [inline]
__arm64_sys_sendmsg+0x80/0x94 net/socket.c:2572
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581


---
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If the bug is already fixed, let syzbot know by replying with:
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If you want to change bug's subsystems, reply with:
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#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4af60700a60c Linux 5.15.119
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1707af7b280000
kernel config: https://syzkaller.appspot.com/x/.config?x=ba2032bf87adc4c7
dashboard link: https://syzkaller.appspot.com/bug?extid=d97cb17541f4a2c2f7ae

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/5a37f09fce32/disk-4af60700.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/28ef8a07cc8f/vmlinux-4af60700.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ff6087a74939/bzImage-4af60700.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+d97cb1...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected

5.15.119-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.0/2703 [HC0[0]:SC0[2]:HE1:SE0] is trying to acquire:
ffffffff8c9dcce0 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:206 [inline]
ffffffff8c9dcce0 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook+0x22/0xc0 mm/slab.h:492

and this task is already holding:

ffff888014d9f108 (&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
run_ksoftirqd+0xc1/0x120 kernel/softirq.c:920
smpboot_thread_fn+0x51b/0x9d0 kernel/smpboot.c:164
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

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:3403 [inline]
wq_numa_init+0x122/0x49f kernel/workqueue.c:5994
workqueue_init+0x18/0x5e1 kernel/workqueue.c:6121
kernel_init_freeable+0x40a/0x5c5 init/main.c:1603
kernel_init+0x19/0x290 init/main.c:1510
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.0/2703:
#0: ffffffff8d9de208 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:72 [inline]
#0: ffffffff8d9de208 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x94c/0xee0 net/core/rtnetlink.c:5590
#1: ffff888014d9f108 (&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:2307
worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
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
run_ksoftirqd+0xc1/0x120 kernel/softirq.c:920
smpboot_thread_fn+0x51b/0x9d0 kernel/smpboot.c:164
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
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:2307
worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
kthread+0x3f6/0x4f0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
}
... key at: [<ffffffff9178e380>] 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:3403 [inline]
wq_numa_init+0x122/0x49f kernel/workqueue.c:5994
workqueue_init+0x18/0x5e1 kernel/workqueue.c:6121
kernel_init_freeable+0x40a/0x5c5 init/main.c:1603
kernel_init+0x19/0x290 init/main.c:1510
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:3403 [inline]
wq_numa_init+0x122/0x49f kernel/workqueue.c:5994
workqueue_init+0x18/0x5e1 kernel/workqueue.c:6121
kernel_init_freeable+0x40a/0x5c5 init/main.c:1603
kernel_init+0x19/0x290 init/main.c:1510
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:3403 [inline]
wq_numa_init+0x122/0x49f kernel/workqueue.c:5994
workqueue_init+0x18/0x5e1 kernel/workqueue.c:6121
kernel_init_freeable+0x40a/0x5c5 init/main.c:1603
kernel_init+0x19/0x290 init/main.c:1510
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
}
... key at: [<ffffffff8c9dcce0>] __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:5593
netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2504
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:1923
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: 2703 Comm: syz-executor.0 Not tainted 5.15.119-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

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:5593
netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2504
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:1923
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: 0033:0x7f9dd7b5b389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9dd60cd168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9dd7c7af80 RCX: 00007f9dd7b5b389
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000005
RBP: 00007f9dd7ba6493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffceb63668f R14: 00007f9dd60cd300 R15: 0000000000022000
</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: 2703, name: syz-executor.0

INFO: lockdep is turned off.
Preemption disabled at:

[<0000000000000000>] 0x0
CPU: 1 PID: 2703 Comm: syz-executor.0 Not tainted 5.15.119-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

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:5593
netlink_rcv_skb+0x1cf/0x410 net/netlink/af_netlink.c:2504
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:1923
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: 0033:0x7f9dd7b5b389
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9dd60cd168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f9dd7c7af80 RCX: 00007f9dd7b5b389
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000005
RBP: 00007f9dd7ba6493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffceb63668f R14: 00007f9dd60cd300 R15: 0000000000022000
</TASK>

[syzbot]

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

[syzbot]