一、实际问题：

1、开机出现原子上下文调度的bug：

[    6.290494] <1>.(1)[285:init]BUG: scheduling while atomic: init/285/0x00000000
[    6.290528] <1>-(1)[285:init][<c010e61c>] (dump_backtrace) from [<c010e954>] (show_stack+0x18/0x1c)
[    6.290533] <1>-(1)[285:init] r6:600b0013 r5:c14556d0 r4:00000000 r3:00040975
[    6.290543] <1>-(1)[285:init][<c010e93c>] (show_stack) from [<c04b5e88>] (dump_stack+0x94/0xa8)
[    6.290551] <1>-(1)[285:init][<c04b5df4>] (dump_stack) from [<c0159a14>] (__schedule_bug+0x58/0x6c)
[    6.290555] <1>-(1)[285:init] r6:c1404a54 r5:c13a4b00 r4:00000000 r3:600b0013
[    6.290561] <1>-(1)[285:init][<c01599bc>] (__schedule_bug) from [<c0ddf568>] (__schedule+0x660/0xa68)
[    6.290564] <1>-(1)[285:init] r4:df68bb00 r3:c13a4b00
[    6.290568] <1>-(1)[285:init][<c0ddef08>] (__schedule) from [<c0ddf9c4>] (schedule+0x54/0xb8)
[    6.290572] <1>-(1)[285:init] r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:00000000
[    6.290574] <1>-(1)[285:init] r4:dd7ca000
[    6.290579] <1>-(1)[285:init][<c0ddf970>] (schedule) from [<c0de3668>] (schedule_hrtimeout_range_clock+0x1ac/0x1b8)
[    6.290582] <1>-(1)[285:init] r4:c1404548 r3:00040975
[    6.290587] <1>-(1)[285:ini