Question about switch_mm function

[Sreejith M M]

On Wed, Mar 25, 2015 at 10:55 PM,  <Valdis.Kletnieks at vt.edu> wrote:
> On Wed, 25 Mar 2015 21:35:22 +0530, Sreejith M M said:
>
>> > This code is handling context switch from a kernel thread back to user mode
>> > thread so TLB entries are invalid translation for user mode thread and do
>> > not correspond to user process pgd. It is Master kernel page table
>> > translation as a result of kernel thread execution.
>> >
>> > -Rajat
>> Hi Rajat,
>>
>> If that is the case, why this code is put under CONFIG_SMP switch?
>
> Vastly simplified because I'm lazy :)
>
> If you look at the code, it's poking the status on *other* CPUs.  That's why
> the cpumask() stuff.
>
> If you're on a single execution unit, you don't have to tell the other
> CPU about the change in state, because there isn't an other CPU.

can you come out of this lazy mode explain this a bit more because I
am a newbie ?or tell me what else I should know before I have to
understand this code

-- 
Regards,
Sreejith