mptcp: fix kmalloc flag in mptcp_pm_nl_get_local_id

mptcp_pm_nl_get_local_id may be called in interrupt context, so we need to
use GFP_ATOMIC flag to allocate memory to avoid sleeping in atomic context.

[  280.209809] BUG: sleeping function called from invalid context at mm/slab.h:498
[  280.209812] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1680, name: kworker/1:3
[  280.209814] INFO: lockdep is turned off.
[  280.209816] CPU: 1 PID: 1680 Comm: kworker/1:3 Tainted: G        W         5.9.0-rc3-mptcp+ #146
[  280.209818] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  280.209820] Workqueue: events mptcp_worker
[  280.209822] Call Trace:
[  280.209824]  <IRQ>
[  280.209826]  dump_stack+0x77/0xa0
[  280.209829]  ___might_sleep.cold+0xa6/0xb6
[  280.209832]  kmem_cache_alloc_trace+0x1d1/0x290
[  280.209835]  mptcp_pm_nl_get_local_id+0x23c/0x410
[  280.209840]  subflow_init_req+0x1e9/0x2ea
[  280.209843]  ? inet_reqsk_alloc+0x1c/0x120
[  280.209845]  ? kmem_cache_alloc+0x264/0x290
[  280.209849]  tcp_conn_request+0x303/0xae0
[  280.209854]  ? printk+0x53/0x6a
[  280.209857]  ? tcp_rcv_state_process+0x28f/0x1374
[  280.209859]  tcp_rcv_state_process+0x28f/0x1374
[  280.209864]  ? tcp_v4_do_rcv+0xb3/0x1f0
[  280.209866]  tcp_v4_do_rcv+0xb3/0x1f0
[  280.209869]  tcp_v4_rcv+0xed6/0xfa0
[  280.209873]  ip_protocol_deliver_rcu+0x28/0x270
[  280.209875]  ip_local_deliver_finish+0x89/0x120
[  280.209877]  ip_local_deliver+0x180/0x220
[  280.209881]  ip_rcv+0x166/0x210
[  280.209885]  __netif_receive_skb_one_core+0x82/0x90
[  280.209888]  process_backlog+0xd6/0x230
[  280.209891]  net_rx_action+0x13a/0x410
[  280.209895]  __do_softirq+0xcf/0x468
[  280.209899]  asm_call_on_stack+0x12/0x20
[  280.209901]  </IRQ>
[  280.209903]  ? ip_finish_output2+0x240/0x9a0
[  280.209906]  do_softirq_own_stack+0x4d/0x60
[  280.209908]  do_softirq.part.0+0x2b/0x60
[  280.209911]  __local_bh_enable_ip+0x9a/0xa0
[  280.209913]  ip_finish_output2+0x264/0x9a0
[  280.209916]  ? rcu_read_lock_held+0x4d/0x60
[  280.209920]  ? ip_output+0x7a/0x250
[  280.209922]  ip_output+0x7a/0x250
[  280.209925]  ? __ip_finish_output+0x330/0x330
[  280.209928]  __ip_queue_xmit+0x1dc/0x5a0
[  280.209931]  __tcp_transmit_skb+0xa0f/0xc70
[  280.209937]  tcp_connect+0xb03/0xff0
[  280.209939]  ? lockdep_hardirqs_on_prepare+0xe7/0x190
[  280.209942]  ? ktime_get_with_offset+0x125/0x150
[  280.209944]  ? trace_hardirqs_on+0x1c/0xe0
[  280.209948]  tcp_v4_connect+0x449/0x550
[  280.209953]  __inet_stream_connect+0xbb/0x320
[  280.209955]  ? mark_held_locks+0x49/0x70
[  280.209958]  ? lockdep_hardirqs_on_prepare+0xe7/0x190
[  280.209960]  ? __local_bh_enable_ip+0x6b/0xa0
[  280.209963]  inet_stream_connect+0x32/0x50
[  280.209966]  __mptcp_subflow_connect+0x1fd/0x242
[  280.209972]  mptcp_pm_create_subflow_or_signal_addr+0x2db/0x600
[  280.209975]  mptcp_worker+0x543/0x7a0
[  280.209980]  process_one_work+0x26d/0x5b0
[  280.209984]  ? process_one_work+0x5b0/0x5b0
[  280.209987]  worker_thread+0x48/0x3d0
[  280.209990]  ? process_one_work+0x5b0/0x5b0
[  280.209993]  kthread+0x117/0x150
[  280.209996]  ? kthread_park+0x80/0x80
[  280.209998]  ret_from_fork+0x22/0x30

Fixes: 01cacb00b3 ("mptcp: add netlink-based PM")
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/pm_netlink.c

@@ -354,7 +354,7 @@ int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
 		return ret;
 
 	/* address not found, add to local list */
-	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+	entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 	if (!entry)
 		return -ENOMEM;