[v5.15] possible deadlock in sch_direct_xmit (2)

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Feb 22, 2024, 2:25:23 PMFeb 22
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Hello,

syzbot found the following issue on:

HEAD commit: 6139f2a02fe0 Linux 5.15.148
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13645264180000
kernel config: https://syzkaller.appspot.com/x/.config?x=c3cfb017ec09dfb8
dashboard link: https://syzkaller.appspot.com/bug?extid=3f44bf8b6f083aa47b0a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/863dea226ad0/disk-6139f2a0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/db1a0715548e/vmlinux-6139f2a0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/edd9bd0f16ff/Image-6139f2a0.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3f44bf...@syzkaller.appspotmail.com

============================================
WARNING: possible recursive locking detected
5.15.148-syzkaller #0 Not tainted
--------------------------------------------
syz-executor.0/6853 is trying to acquire lock:
ffff0000cd71a398 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
ffff0000cd71a398 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4429 [inline]
ffff0000cd71a398 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x15c/0x484 net/sched/sch_generic.c:340

but task is already holding lock:
ffff0000d7747c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
ffff0000d7747c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4429 [inline]
ffff0000d7747c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x15c/0x484 net/sched/sch_generic.c:340

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(_xmit_ETHER#2);
lock(_xmit_ETHER#2);

*** DEADLOCK ***

May be due to missing lock nesting notation

12 locks held by syz-executor.0/6853:
#0: ffff800014af15e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:268
#1: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268
#2: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268
#3: ffff0000d67c4258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
#3: ffff0000d67c4258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x130/0x2bc include/net/sch_generic.h:173
#4: ffff0000d7747c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:363 [inline]
#4: ffff0000d7747c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: __netif_tx_lock include/linux/netdevice.h:4429 [inline]
#4: ffff0000d7747c98 (_xmit_ETHER#2){+.-.}-{2:2}, at: sch_direct_xmit+0x15c/0x484 net/sched/sch_generic.c:340
#5: ffff0000d7438f20 (k-slock-AF_INET6){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
#5: ffff0000d7438f20 (k-slock-AF_INET6){+...}-{2:2}, at: icmpv6_xmit_lock+0x100/0x188 net/ipv6/icmp.c:118
#6: ffff800014af15e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:268
#7: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268
#8: ffff800014af15e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:268
#9: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268
#10: ffff800014af1640 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire+0x18/0x54 include/linux/rcupdate.h:268
#11: ffff00010ab86258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: spin_trylock include/linux/spinlock.h:373 [inline]
#11: ffff00010ab86258 (dev->qdisc_tx_busylock ?: &qdisc_tx_busylock){+...}-{2:2}, at: qdisc_run_begin+0x130/0x2bc include/net/sch_generic.h:173

stack backtrace:
CPU: 1 PID: 6853 Comm: syz-executor.0 Not tainted 5.15.148-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Call trace:
dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
__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+0x62bc/0x7638 kernel/locking/lockdep.c:5012
lock_acquire+0x240/0x77c kernel/locking/lockdep.c:5623
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0xb0/0x10c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:363 [inline]
__netif_tx_lock include/linux/netdevice.h:4429 [inline]
sch_direct_xmit+0x15c/0x484 net/sched/sch_generic.c:340
__dev_xmit_skb net/core/dev.c:3844 [inline]
__dev_queue_xmit+0x14b4/0x2a6c net/core/dev.c:4213
dev_queue_xmit+0x24/0x34 net/core/dev.c:4281
neigh_hh_output include/net/neighbour.h:493 [inline]
neigh_output include/net/neighbour.h:507 [inline]
ip6_finish_output2+0x1314/0x1c4c net/ipv6/ip6_output.c:126
__ip6_finish_output+0x580/0x6ec net/ipv6/ip6_output.c:197
ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:207
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip6_output+0x270/0x594 net/ipv6/ip6_output.c:230
dst_output include/net/dst.h:443 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
ndisc_send_skb+0xbf8/0x1788 net/ipv6/ndisc.c:509
ndisc_send_ns+0x538/0x6ec net/ipv6/ndisc.c:651
ndisc_solicit+0x2f4/0x47c
neigh_probe+0xc4/0x138 net/core/neighbour.c:1017
__neigh_event_send+0xca4/0x1338 net/core/neighbour.c:1178
neigh_event_send include/net/neighbour.h:438 [inline]
neigh_resolve_output+0x178/0x5dc net/core/neighbour.c:1488
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x1348/0x1c4c net/ipv6/ip6_output.c:126
__ip6_finish_output+0x580/0x6ec net/ipv6/ip6_output.c:197
ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:207
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip6_output+0x270/0x594 net/ipv6/ip6_output.c:230
dst_output include/net/dst.h:443 [inline]
ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161
ip6_send_skb+0x118/0x428 net/ipv6/ip6_output.c:1943
ip6_push_pending_frames+0xd0/0x118 net/ipv6/ip6_output.c:1963
icmpv6_push_pending_frames+0x244/0x398 net/ipv6/icmp.c:311
icmp6_send+0x11a4/0x1b18 net/ipv6/icmp.c:630
__icmpv6_send include/linux/icmpv6.h:28 [inline]
icmpv6_send include/linux/icmpv6.h:49 [inline]
ip6_link_failure+0x44/0x4a8 net/ipv6/route.c:2790
dst_link_failure+0x11c/0x160 include/net/dst.h:422
ip_tunnel_xmit+0x16e0/0x2358 net/ipv4/ip_tunnel.c:816
__gre_xmit net/ipv4/ip_gre.c:469 [inline]
erspan_xmit+0x9cc/0x14cc net/ipv4/ip_gre.c:718
__netdev_start_xmit include/linux/netdevice.h:5019 [inline]
netdev_start_xmit include/linux/netdevice.h:5033 [inline]
xmit_one net/core/dev.c:3617 [inline]
dev_hard_start_xmit+0x2bc/0x92c net/core/dev.c:3633
sch_direct_xmit+0x2e0/0x484 net/sched/sch_generic.c:342
__dev_xmit_skb net/core/dev.c:3844 [inline]
__dev_queue_xmit+0x14b4/0x2a6c net/core/dev.c:4213
dev_queue_xmit+0x24/0x34 net/core/dev.c:4281
neigh_resolve_output+0x52c/0x5dc net/core/neighbour.c:1504
neigh_output include/net/neighbour.h:509 [inline]
ip6_finish_output2+0x1348/0x1c4c net/ipv6/ip6_output.c:126
__ip6_finish_output+0x580/0x6ec net/ipv6/ip6_output.c:197
ip6_finish_output+0x40/0x218 net/ipv6/ip6_output.c:207
NF_HOOK_COND include/linux/netfilter.h:291 [inline]
ip6_output+0x270/0x594 net/ipv6/ip6_output.c:230
dst_output include/net/dst.h:443 [inline]
NF_HOOK include/linux/netfilter.h:302 [inline]
rawv6_send_hdrinc+0xd64/0x1c14 net/ipv6/raw.c:691
rawv6_sendmsg+0x1074/0x1bcc net/ipv6/raw.c:949
inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:825
sock_sendmsg_nosec net/socket.c:704 [inline]
__sock_sendmsg net/socket.c:716 [inline]
sock_write_iter+0x2b0/0x3f8 net/socket.c:1079
call_write_iter include/linux/fs.h:2146 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x87c/0xb3c fs/read_write.c:594
ksys_write+0x15c/0x26c fs/read_write.c:647
__do_sys_write fs/read_write.c:659 [inline]
__se_sys_write fs/read_write.c:656 [inline]
__arm64_sys_write+0x7c/0x90 fs/read_write.c:656
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584


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