possible deadlock in xfrm_policy_delete

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa35f24 Add linux-next specific files for 20200916
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1122e2d9900000
kernel config: https://syzkaller.appspot.com/x/.config?x=6bdb7e39caf48f53
dashboard link: https://syzkaller.appspot.com/bug?extid=c32502fd255cb3a44048
compiler: gcc (GCC) 10.1.0-syz 20200507

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c32502...@syzkaller.appspotmail.com

=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.9.0-rc5-next-20200916-syzkaller #0 Not tainted
-----------------------------------------------------
syz-executor.1/13775 [HC0[0]:SC0[4]:HE1:SE0] is trying to acquire:
ffff88805ee15a58 (&net->xfrm.xfrm_policy_lock){+...}-{2:2}, at: spin_lock_bh include/linux/spinlock.h:359 [inline]
ffff88805ee15a58 (&net->xfrm.xfrm_policy_lock){+...}-{2:2}, at: xfrm_policy_delete+0x3a/0x90 net/xfrm/xfrm_policy.c:2236

and this task is already holding:
ffff8880a811b1e0 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline]
ffff8880a811b1e0 (k-slock-AF_INET6){+.-.}-{2:2}, at: tcp_close+0x6e3/0x1200 net/ipv4/tcp.c:2503
which would create a new lock dependency:
(k-slock-AF_INET6){+.-.}-{2:2} -> (&net->xfrm.xfrm_policy_lock){+...}-{2:2}

but this new dependency connects a SOFTIRQ-irq-safe lock:
(k-slock-AF_INET6){+.-.}-{2:2}

... which became SOFTIRQ-irq-safe at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:354 [inline]
sctp_rcv+0xd96/0x2d50 net/sctp/input.c:231
sctp6_rcv+0x12/0x30 net/sctp/ipv6.c:1056
ip6_protocol_deliver_rcu+0x2e8/0x1660 net/ipv6/ip6_input.c:433
ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
dst_input include/net/dst.h:449 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
__netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
process_backlog+0x2e1/0x8e0 net/core/dev.c:6286
napi_poll net/core/dev.c:6730 [inline]
net_rx_action+0x572/0x1300 net/core/dev.c:6800
__do_softirq+0x202/0xa42 kernel/softirq.c:298
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:786
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77
do_softirq kernel/softirq.c:343 [inline]
do_softirq+0x154/0x1b0 kernel/softirq.c:330
__local_bh_enable_ip+0x196/0x1f0 kernel/softirq.c:195
local_bh_enable include/linux/bottom_half.h:32 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:730 [inline]
ip6_finish_output2+0x953/0x1770 net/ipv6/ip6_output.c:118
__ip6_finish_output net/ipv6/ip6_output.c:143 [inline]
__ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128
ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
NF_HOOK_COND include/linux/netfilter.h:290 [inline]
ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176
dst_output include/net/dst.h:443 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ip6_xmit+0x1258/0x1e80 net/ipv6/ip6_output.c:280
sctp_v6_xmit+0x339/0x650 net/sctp/ipv6.c:217
sctp_packet_transmit+0x20d7/0x3240 net/sctp/output.c:629
sctp_packet_singleton net/sctp/outqueue.c:773 [inline]
sctp_outq_flush_ctrl.constprop.0+0x6d3/0xc40 net/sctp/outqueue.c:904
sctp_outq_flush+0xfb/0x2380 net/sctp/outqueue.c:1186
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1801 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
sctp_do_sm+0x4d0/0x4d80 net/sctp/sm_sideeffect.c:1156
sctp_primitive_ASSOCIATE+0x98/0xc0 net/sctp/primitive.c:73
__sctp_connect+0x9a7/0xc00 net/sctp/socket.c:1217
__sctp_setsockopt_connectx net/sctp/socket.c:1319 [inline]
__sctp_setsockopt_connectx+0xfa/0x140 net/sctp/socket.c:1294
sctp_setsockopt_connectx_old net/sctp/socket.c:1330 [inline]
sctp_setsockopt+0x1b69/0x97f0 net/sctp/socket.c:4482
__sys_setsockopt+0x2db/0x610 net/socket.c:2132
__do_sys_setsockopt net/socket.c:2143 [inline]
__se_sys_setsockopt net/socket.c:2140 [inline]
__x64_sys_setsockopt+0xba/0x150 net/socket.c:2140
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

to a SOFTIRQ-irq-unsafe lock:
(&s->seqcount#12){+.+.}-{0:0}

... which became SOFTIRQ-irq-unsafe at:
...
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
write_seqlock include/linux/seqlock.h:883 [inline]
xfrm_set_spdinfo+0x302/0x660 net/xfrm/xfrm_user.c:1185
xfrm_user_rcv_msg+0x414/0x700 net/xfrm/xfrm_user.c:2684
netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2692
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2362
___sys_sendmsg+0xf3/0x170 net/socket.c:2416
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2449
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

other info that might help us debug this:

Chain exists of:
k-slock-AF_INET6 --> &net->xfrm.xfrm_policy_lock --> &s->seqcount#12

Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&s->seqcount#12);
local_irq_disable();
lock(k-slock-AF_INET6);
lock(&net->xfrm.xfrm_policy_lock);
<Interrupt>
lock(k-slock-AF_INET6);

*** DEADLOCK ***

4 locks held by syz-executor.1/13775:
#0: ffff888056c2dc90 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:782 [inline]
#0: ffff888056c2dc90 (&sb->s_type->i_mutex_key#12){+.+.}-{3:3}, at: __sock_release+0x86/0x280 net/socket.c:595
#1: ffff8880535efd78 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: smc_clcsock_release+0x71/0xe0 net/smc/smc_close.c:30
#2: ffff8880a811b260 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1581 [inline]
#2: ffff8880a811b260 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: tcp_close+0x25/0x1200 net/ipv4/tcp.c:2413
#3: ffff8880a811b1e0 (k-slock-AF_INET6){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:354 [inline]
#3: ffff8880a811b1e0 (k-slock-AF_INET6){+.-.}-{2:2}, at: tcp_close+0x6e3/0x1200 net/ipv4/tcp.c:2503

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (k-slock-AF_INET6){+.-.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
spin_lock_bh include/linux/spinlock.h:359 [inline]
lock_sock_nested+0x3b/0x110 net/core/sock.c:3034
lock_sock include/net/sock.h:1581 [inline]
tcp_sock_set_nodelay+0x18/0xe0 net/ipv4/tcp.c:2916
rds_tcp_listen_init+0x132/0x4d0 net/rds/tcp_listen.c:275
rds_tcp_init_net+0x265/0x4e0 net/rds/tcp.c:559
ops_init+0xaf/0x470 net/core/net_namespace.c:151
__register_pernet_operations net/core/net_namespace.c:1140 [inline]
register_pernet_operations+0x35a/0x850 net/core/net_namespace.c:1217
register_pernet_device+0x26/0x70 net/core/net_namespace.c:1304
rds_tcp_init+0x77/0xe0 net/rds/tcp.c:717
do_one_initcall+0x103/0x6f0 init/main.c:1204
do_initcall_level init/main.c:1277 [inline]
do_initcalls init/main.c:1293 [inline]
do_basic_setup init/main.c:1313 [inline]
kernel_init_freeable+0x5e9/0x66d init/main.c:1512
kernel_init+0xd/0x1c0 init/main.c:1402
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
IN-SOFTIRQ-W at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:354 [inline]
sctp_rcv+0xd96/0x2d50 net/sctp/input.c:231
sctp6_rcv+0x12/0x30 net/sctp/ipv6.c:1056
ip6_protocol_deliver_rcu+0x2e8/0x1660 net/ipv6/ip6_input.c:433
ip6_input_finish+0x7f/0x160 net/ipv6/ip6_input.c:474
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ip6_input+0x9c/0xd0 net/ipv6/ip6_input.c:483
dst_input include/net/dst.h:449 [inline]
ip6_rcv_finish net/ipv6/ip6_input.c:76 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ipv6_rcv+0x28e/0x3c0 net/ipv6/ip6_input.c:307
__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5287
__netif_receive_skb+0x27/0x1c0 net/core/dev.c:5401
process_backlog+0x2e1/0x8e0 net/core/dev.c:6286
napi_poll net/core/dev.c:6730 [inline]
net_rx_action+0x572/0x1300 net/core/dev.c:6800
__do_softirq+0x202/0xa42 kernel/softirq.c:298
asm_call_on_stack+0xf/0x20 arch/x86/entry/entry_64.S:786
__run_on_irqstack arch/x86/include/asm/irq_stack.h:22 [inline]
run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:48 [inline]
do_softirq_own_stack+0x9d/0xd0 arch/x86/kernel/irq_64.c:77
do_softirq kernel/softirq.c:343 [inline]
do_softirq+0x154/0x1b0 kernel/softirq.c:330
__local_bh_enable_ip+0x196/0x1f0 kernel/softirq.c:195
local_bh_enable include/linux/bottom_half.h:32 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:730 [inline]
ip6_finish_output2+0x953/0x1770 net/ipv6/ip6_output.c:118
__ip6_finish_output net/ipv6/ip6_output.c:143 [inline]
__ip6_finish_output+0x447/0xab0 net/ipv6/ip6_output.c:128
ip6_finish_output+0x34/0x1f0 net/ipv6/ip6_output.c:153
NF_HOOK_COND include/linux/netfilter.h:290 [inline]
ip6_output+0x1db/0x520 net/ipv6/ip6_output.c:176
dst_output include/net/dst.h:443 [inline]
NF_HOOK include/linux/netfilter.h:301 [inline]
NF_HOOK include/linux/netfilter.h:295 [inline]
ip6_xmit+0x1258/0x1e80 net/ipv6/ip6_output.c:280
sctp_v6_xmit+0x339/0x650 net/sctp/ipv6.c:217
sctp_packet_transmit+0x20d7/0x3240 net/sctp/output.c:629
sctp_packet_singleton net/sctp/outqueue.c:773 [inline]
sctp_outq_flush_ctrl.constprop.0+0x6d3/0xc40 net/sctp/outqueue.c:904
sctp_outq_flush+0xfb/0x2380 net/sctp/outqueue.c:1186
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1801 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1185 [inline]
sctp_do_sm+0x4d0/0x4d80 net/sctp/sm_sideeffect.c:1156
sctp_primitive_ASSOCIATE+0x98/0xc0 net/sctp/primitive.c:73
__sctp_connect+0x9a7/0xc00 net/sctp/socket.c:1217
__sctp_setsockopt_connectx net/sctp/socket.c:1319 [inline]
__sctp_setsockopt_connectx+0xfa/0x140 net/sctp/socket.c:1294
sctp_setsockopt_connectx_old net/sctp/socket.c:1330 [inline]
sctp_setsockopt+0x1b69/0x97f0 net/sctp/socket.c:4482
__sys_setsockopt+0x2db/0x610 net/socket.c:2132
__do_sys_setsockopt net/socket.c:2143 [inline]
__se_sys_setsockopt net/socket.c:2140 [inline]
__x64_sys_setsockopt+0xba/0x150 net/socket.c:2140
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
INITIAL USE at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
spin_lock_bh include/linux/spinlock.h:359 [inline]
lock_sock_nested+0x3b/0x110 net/core/sock.c:3034
lock_sock include/net/sock.h:1581 [inline]
tcp_sock_set_nodelay+0x18/0xe0 net/ipv4/tcp.c:2916
rds_tcp_listen_init+0x132/0x4d0 net/rds/tcp_listen.c:275
rds_tcp_init_net+0x265/0x4e0 net/rds/tcp.c:559
ops_init+0xaf/0x470 net/core/net_namespace.c:151
__register_pernet_operations net/core/net_namespace.c:1140 [inline]
register_pernet_operations+0x35a/0x850 net/core/net_namespace.c:1217
register_pernet_device+0x26/0x70 net/core/net_namespace.c:1304
rds_tcp_init+0x77/0xe0 net/rds/tcp.c:717
do_one_initcall+0x103/0x6f0 init/main.c:1204
do_initcall_level init/main.c:1277 [inline]
do_initcalls init/main.c:1293 [inline]
do_basic_setup init/main.c:1313 [inline]
kernel_init_freeable+0x5e9/0x66d init/main.c:1512
kernel_init+0xd/0x1c0 init/main.c:1402
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
}
... key at: [<ffffffff8d91b7c0>] af_family_kern_slock_keys+0xa0/0x300
... acquired at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
spin_lock_bh include/linux/spinlock.h:359 [inline]
xfrm_policy_delete+0x3a/0x90 net/xfrm/xfrm_policy.c:2236
xfrm_sk_free_policy include/net/xfrm.h:1192 [inline]
inet_csk_destroy_sock+0x35b/0x490 net/ipv4/inet_connection_sock.c:887
tcp_close+0xdb5/0x1200 net/ipv4/tcp.c:2570
inet_release+0x12e/0x280 net/ipv4/af_inet.c:431
inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:475
__sock_release net/socket.c:596 [inline]
sock_release+0x87/0x1b0 net/socket.c:624
smc_clcsock_release+0xb3/0xe0 net/smc/smc_close.c:34
__smc_release+0x393/0x580 net/smc/af_smc.c:164
smc_release+0x167/0x490 net/smc/af_smc.c:199
__sock_release+0xcd/0x280 net/socket.c:596
sock_close+0x18/0x20 net/socket.c:1277
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:141
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190
syscall_exit_to_user_mode+0x7a/0x2c0 kernel/entry/common.c:265
entry_SYSCALL_64_after_hwframe+0x44/0xa9


the dependencies between the lock to be acquired
and SOFTIRQ-irq-unsafe lock:
-> (&s->seqcount#12){+.+.}-{0:0} {
HARDIRQ-ON-W at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
__xfrm_policy_inexact_prune_bin+0xbc/0x1040 net/xfrm/xfrm_policy.c:1077
xfrm_policy_inexact_insert+0x48c/0xbb0 net/xfrm/xfrm_policy.c:1205
xfrm_policy_insert+0x4f3/0x840 net/xfrm/xfrm_policy.c:1572
pfkey_spdadd+0xfb1/0x1550 net/key/af_key.c:2332
pfkey_process+0x66d/0x7a0 net/key/af_key.c:2841
pfkey_sendmsg+0x42d/0x800 net/key/af_key.c:3680
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2362
___sys_sendmsg+0xf3/0x170 net/socket.c:2416
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2449
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
SOFTIRQ-ON-W at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
write_seqlock include/linux/seqlock.h:883 [inline]
xfrm_set_spdinfo+0x302/0x660 net/xfrm/xfrm_user.c:1185
xfrm_user_rcv_msg+0x414/0x700 net/xfrm/xfrm_user.c:2684
netlink_rcv_skb+0x15a/0x430 net/netlink/af_netlink.c:2470
xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2692
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2362
___sys_sendmsg+0xf3/0x170 net/socket.c:2416
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2449
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
INITIAL USE at:
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
write_seqcount_t_begin_nested include/linux/seqlock.h:509 [inline]
write_seqcount_t_begin include/linux/seqlock.h:535 [inline]
__xfrm_policy_inexact_prune_bin+0xbc/0x1040 net/xfrm/xfrm_policy.c:1077
xfrm_policy_inexact_insert+0x48c/0xbb0 net/xfrm/xfrm_policy.c:1205
xfrm_policy_insert+0x4f3/0x840 net/xfrm/xfrm_policy.c:1572
pfkey_spdadd+0xfb1/0x1550 net/key/af_key.c:2332
pfkey_process+0x66d/0x7a0 net/key/af_key.c:2841
pfkey_sendmsg+0x42d/0x800 net/key/af_key.c:3680
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:671
____sys_sendmsg+0x6e8/0x810 net/socket.c:2362
___sys_sendmsg+0xf3/0x170 net/socket.c:2416
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2449
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
(null) at:
general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 1 PID: 13775 Comm: syz-executor.1 Not tainted 5.9.0-rc5-next-20200916-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:print_lock_trace kernel/locking/lockdep.c:1751 [inline]
RIP: 0010:print_lock_class_header kernel/locking/lockdep.c:2240 [inline]
RIP: 0010:print_shortest_lock_dependencies.cold+0x110/0x2af kernel/locking/lockdep.c:2263
Code: 48 8b 04 24 48 c1 e8 03 42 80 3c 20 00 74 09 48 8b 3c 24 e8 c1 2b d9 f9 48 8b 04 24 48 8b 00 48 8d 78 14 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 22 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85
RSP: 0018:ffffc900075af7c8 EFLAGS: 00010002
RAX: 000000000000000c RBX: ffffffff8cc6d360 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff815c26b7 RDI: 0000000000000020
RBP: ffffc900075af980 R08: 0000000000000004 R09: ffff8880ae720f8b
R10: 0000000000000000 R11: 6c756e2820202020 R12: dffffc0000000000
R13: ffffffff8ca37188 R14: 0000000000000009 R15: 0000000000000001
FS: 0000000002f84940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000c40 CR3: 00000000937e4000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
print_bad_irq_dependency kernel/locking/lockdep.c:2402 [inline]
check_irq_usage.cold+0x46b/0x5b0 kernel/locking/lockdep.c:2634
check_prev_add kernel/locking/lockdep.c:2823 [inline]
check_prevs_add kernel/locking/lockdep.c:2944 [inline]
validate_chain kernel/locking/lockdep.c:3562 [inline]
__lock_acquire+0x2800/0x55d0 kernel/locking/lockdep.c:4796
lock_acquire+0x1f2/0xaa0 kernel/locking/lockdep.c:5398
__raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
_raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175
spin_lock_bh include/linux/spinlock.h:359 [inline]
xfrm_policy_delete+0x3a/0x90 net/xfrm/xfrm_policy.c:2236
xfrm_sk_free_policy include/net/xfrm.h:1192 [inline]
inet_csk_destroy_sock+0x35b/0x490 net/ipv4/inet_connection_sock.c:887
tcp_close+0xdb5/0x1200 net/ipv4/tcp.c:2570
inet_release+0x12e/0x280 net/ipv4/af_inet.c:431
inet6_release+0x4c/0x70 net/ipv6/af_inet6.c:475
__sock_release net/socket.c:596 [inline]
sock_release+0x87/0x1b0 net/socket.c:624
smc_clcsock_release+0xb3/0xe0 net/smc/smc_close.c:34
__smc_release+0x393/0x580 net/smc/af_smc.c:164
smc_release+0x167/0x490 net/smc/af_smc.c:199
__sock_release+0xcd/0x280 net/socket.c:596
sock_close+0x18/0x20 net/socket.c:1277
__fput+0x285/0x920 fs/file_table.c:281
task_work_run+0xdd/0x190 kernel/task_work.c:141
tracehook_notify_resume include/linux/tracehook.h:188 [inline]
exit_to_user_mode_loop kernel/entry/common.c:163 [inline]
exit_to_user_mode_prepare+0x1e2/0x1f0 kernel/entry/common.c:190
syscall_exit_to_user_mode+0x7a/0x2c0 kernel/entry/common.c:265
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x416f41
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffe6c10fe30 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000416f41
RDX: 0000000000000000 RSI: 00000000000009bb RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000020e589bb R09: 0000000020e589bf
R10: 00007ffe6c10ff20 R11: 0000000000000293 R12: 00000000011902c8
R13: 0000000000053600 R14: ffffffffffffffff R15: 000000000118cf4c
Modules linked in:
---[ end trace 71b6ce44d53da1fe ]---
RIP: 0010:print_lock_trace kernel/locking/lockdep.c:1751 [inline]
RIP: 0010:print_lock_class_header kernel/locking/lockdep.c:2240 [inline]
RIP: 0010:print_shortest_lock_dependencies.cold+0x110/0x2af kernel/locking/lockdep.c:2263
Code: 48 8b 04 24 48 c1 e8 03 42 80 3c 20 00 74 09 48 8b 3c 24 e8 c1 2b d9 f9 48 8b 04 24 48 8b 00 48 8d 78 14 48 89 fa 48 c1 ea 03 <42> 0f b6 0c 22 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85
RSP: 0018:ffffc900075af7c8 EFLAGS: 00010002
RAX: 000000000000000c RBX: ffffffff8cc6d360 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff815c26b7 RDI: 0000000000000020
RBP: ffffc900075af980 R08: 0000000000000004 R09: ffff8880ae720f8b
R10: 0000000000000000 R11: 6c756e2820202020 R12: dffffc0000000000
R13: ffffffff8ca37188 R14: 0000000000000009 R15: 0000000000000001
FS: 0000000002f84940(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000c40 CR3: 00000000937e4000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[Herbert Xu]

What's going on with all these bogus lockdep reports?

These are two completely different locks, one is for TCP and the
other is for SCTP. Why is lockdep suddenly beoming confused about
this?

FWIW this flood of bogus reports started on 16/Sep.

Cheers,
--
Email: Herbert Xu <her...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

[Dmitry Vyukov]

FWIW one of the dups of this issue was bisected to:

commit 1909760f5fc3f123e47b4e24e0ccdc0fc8f3f106
Author: Ahmed S. Darwish <a.da...@linutronix.de>
Date: Fri Sep 4 15:32:31 2020 +0000

seqlock: PREEMPT_RT: Do not starve seqlock_t writers

Can it be related?


A number of other new lockdep reports were bisected to the following
one, which was true intentional root cause of these, but it looks a
bit too old to cause the xfrm reports:

commit f08e3888574d490b31481eef6d84c61bedba7a47
Author: Boqun Feng <boqun...@gmail.com>
Date: Fri Aug 7 07:42:30 2020 +0000

lockdep: Fix recursive read lock related safe->unsafe detection

[Herbert Xu]

On Thu, Sep 24, 2020 at 06:44:12AM +0200, Dmitry Vyukov wrote:
>
> FWIW one of the dups of this issue was bisected to:
>
> commit 1909760f5fc3f123e47b4e24e0ccdc0fc8f3f106
> Author: Ahmed S. Darwish <a.da...@linutronix.de>
> Date: Fri Sep 4 15:32:31 2020 +0000
>
> seqlock: PREEMPT_RT: Do not starve seqlock_t writers
>
> Can it be related?

Whether there is a genuine problem or not, the lockdep report
that I quoted is simply non-sensical because it's considering
two distinct seqlocks to be the same lock.

I don't think the lockdep issue has anything to do with the commit
question because this commit is specific to seqlocks. There is
another syzbot report in this pile that mixed the SCTP socket lock
with the TCP socket lock and those are not seqlocks.

It's almost as if when a spinlock is freed and reallocated lockdep
is not clearing the existing state.

[pet...@infradead.org]

On Thu, Sep 24, 2020 at 06:44:12AM +0200, Dmitry Vyukov wrote:

> On Thu, Sep 24, 2020 at 6:36 AM Herbert Xu <her...@gondor.apana.org.au> wrote:
> > > (k-slock-AF_INET6){+.-.}-{2:2}

That's a seqlock.

> > What's going on with all these bogus lockdep reports?
> >
> > These are two completely different locks, one is for TCP and the
> > other is for SCTP. Why is lockdep suddenly beoming confused about
> > this?
> >
> > FWIW this flood of bogus reports started on 16/Sep.
>
>
> FWIW one of the dups of this issue was bisected to:
>
> commit 1909760f5fc3f123e47b4e24e0ccdc0fc8f3f106
> Author: Ahmed S. Darwish <a.da...@linutronix.de>
> Date: Fri Sep 4 15:32:31 2020 +0000
>
> seqlock: PREEMPT_RT: Do not starve seqlock_t writers
>
> Can it be related?

Did that tree you're testing include 267580db047e ("seqlock: Unbreak
lockdep") ?

[Herbert Xu]

On Thu, Sep 24, 2020 at 09:30:03AM +0200, pet...@infradead.org wrote:
> On Thu, Sep 24, 2020 at 06:44:12AM +0200, Dmitry Vyukov wrote:
> > On Thu, Sep 24, 2020 at 6:36 AM Herbert Xu <her...@gondor.apana.org.au> wrote:
> > > > (k-slock-AF_INET6){+.-.}-{2:2}
>
> That's a seqlock.

Are you sure? Line 2503 in net/ipv4/tcp.c says

bh_lock_sock(sk);

> Did that tree you're testing include 267580db047e ("seqlock: Unbreak
> lockdep") ?

According to

https://syzkaller.appspot.com/bug?extid=c32502fd255cb3a44048

the git tree used was

https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/tree/include?id=5fa35f247b563a7893f3f68f19d00ace2ccf3dff

so no it doesn't contain that patch.

Hopefully this would address those seqlock backtraces. But what
about this particular one which is caused by the socket lock?

Thanks,

[syzbot]

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