wpa_supplicant appears to be delaying system startup. dmesg claims it has a problem. It sometimes happens multiple times during a startup. 36.710435] INFO: rcu_sched self-detected stall on CPU [ 36.710443] 1-...: (21000 ticks this GP) idle=80d/140000000000001/0 softirq=4749/4752 fqs=7000 [ 36.710446] (t=21001 jiffies g=2074 c=2073 q=1832) [ 36.710449] Task dump for CPU 1: [ 36.710452] wpa_supplicant R running task 13616 2707 1 0x00000008 [ 36.710460] ffffffff81c2d740 ffff88017fc83da8 ffffffff8109b9e2 0000000000000001 [ 36.710464] ffffffff81c2d740 ffff88017fc83dc0 ffffffff8109dd24 0000000000000002 [ 36.710467] ffff88017fc83df0 ffffffff810c8d66 ffff88017fc92e80 ffffffff81c2d740 [ 36.710471] Call Trace: [ 36.710473] <IRQ> [<ffffffff8109b9e2>] sched_show_task+0xc2/0x120 [ 36.710484] [<ffffffff8109dd24>] dump_cpu_task+0x34/0x40 [ 36.710488] [<ffffffff810c8d66>] rcu_dump_cpu_stacks+0x86/0xc0 [ 36.710492] [<ffffffff810cc745>] rcu_check_callbacks+0x4b5/0x7a0 [ 36.710496] [<ffffffff8110c747>] ? acct_account_cputime+0x17/0x20 [ 36.710501] [<ffffffff810e03b0>] ? tick_sched_do_timer+0x30/0x30 [ 36.710505] [<ffffffff810d1654>] update_process_times+0x34/0x60 [ 36.710508] [<ffffffff810dfe51>] tick_sched_handle.isra.15+0x31/0x40 [ 36.710511] [<ffffffff810e03e8>] tick_sched_timer+0x38/0x70 [ 36.710514] [<ffffffff810d2280>] __hrtimer_run_queues+0xf0/0x260 [ 36.710517] [<ffffffff810d26c3>] hrtimer_interrupt+0xa3/0x1a0 [ 36.710522] [<ffffffff81034b23>] local_apic_timer_interrupt+0x33/0x60 [ 36.710525] [<ffffffff81035578>] smp_apic_timer_interrupt+0x38/0x50 [ 36.710530] [<ffffffff8185fd51>] apic_timer_interrupt+0x81/0x90 [ 36.710531] <EOI> [<ffffffff8134d64e>] ? delay_tsc+0x1e/0x50 [ 36.710539] [<ffffffff8134d5c7>] __const_udelay+0x27/0x30 [ 36.710544] [<ffffffff8159dd2e>] rtl8723_fw_free_to_go+0xae/0x100 [ 36.710547] [<ffffffff8159e046>] rtl8723_download_fw+0xb6/0x130 [ 36.710550] [<ffffffff8158fecc>] rtl8723be_hw_init+0xc9c/0x1790 [ 36.710554] [<ffffffff81583889>] rtl_ps_enable_nic+0x29/0x70 [ 36.710558] [<ffffffff8159585e>] rtl8723be_phy_set_rf_power_state+0x34e/0x390 [ 36.710561] [<ffffffff81583b60>] rtl_ps_set_rf_state+0x120/0x170 [ 36.710564] [<ffffffff81583be8>] _rtl_ps_inactive_ps+0x38/0xb0 [ 36.710567] [<ffffffff81583ce2>] rtl_ips_nic_on+0x82/0xb0 [ 36.710571] [<ffffffff8158158d>] rtl_op_config+0x1fd/0x400 [ 36.710576] [<ffffffff817fc708>] ieee80211_hw_config+0x68/0x350 [ 36.710580] [<ffffffff818106ad>] ieee80211_recalc_idle+0x1d/0x20 [ 36.710583] [<ffffffff818060be>] __ieee80211_start_scan+0x22e/0x6f0 [ 36.710586] [<ffffffff8180739b>] ieee80211_request_scan+0x2b/0x50 [ 36.710590] [<ffffffff81815c33>] ieee80211_scan+0x63/0xa0 [ 36.710594] [<ffffffff817d90db>] nl80211_trigger_scan+0x60b/0x6a0 [ 36.710599] [<ffffffff816b8145>] genl_family_rcv_msg+0x185/0x340 [ 36.710602] [<ffffffff816b8300>] ? genl_family_rcv_msg+0x340/0x340 [ 36.710605] [<ffffffff816b8370>] genl_rcv_msg+0x70/0xb0 [ 36.710608] [<ffffffff816b7932>] netlink_rcv_skb+0x92/0xb0 [ 36.710611] [<ffffffff816b7fa3>] genl_rcv+0x23/0x40 [ 36.710614] [<ffffffff816b7357>] netlink_unicast+0x157/0x200 [ 36.710617] [<ffffffff816b76f3>] netlink_sendmsg+0x2f3/0x370 [ 36.710621] [<ffffffff81676480>] sock_sendmsg+0x30/0x40 [ 36.710625] [<ffffffff81677039>] ___sys_sendmsg+0x289/0x320 [ 36.710629] [<ffffffff81159e6a>] ? __inc_zone_page_state+0x2a/0x30 [ 36.710633] [<ffffffff81172635>] ? page_add_file_rmap+0x15/0x20 [ 36.710637] [<ffffffff8116740e>] ? do_set_pte+0x7e/0xc0 [ 36.710641] [<ffffffff8113e59f>] ? unlock_page+0x5f/0x70 [ 36.710644] [<ffffffff8113eac5>] ? filemap_map_pages+0x215/0x220 [ 36.710648] [<ffffffff81168ba2>] ? handle_mm_fault+0xc62/0xff0 [ 36.710651] [<ffffffff816778fd>] __sys_sendmsg+0x3d/0x70 [ 36.710655] [<ffffffff81677939>] SyS_sendmsg+0x9/0x10 [ 36.710658] [<ffffffff8185f01b>] entry_SYSCALL_64_fastpath+0x12/0x6e
