Question about switch_mm function

[Rajat Sharma]

On Mar 25, 2015 10:31 AM, "Sreejith M M" <sreejith.mm at gmail.com> wrote:
>
> 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

Valdis is talking about lazy tlb flush, not him being lazy. Otherwise he
wouldn't have replied at all :)
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