Re: [PATCH linux-next] x86/mm: Fix compile warning in remove_pagetable()

[Tang Chen]

On 02/06/2013 04:27 PM, David Rientjes wrote:
> On Tue, 5 Feb 2013, Shuah Khan wrote:
>
> > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> > index 67bad4b..ed78400 100644
> > --- a/arch/x86/mm/init_64.c
> > +++ b/arch/x86/mm/init_64.c
> > @@ -987,7 +987,7 @@ remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end,
> >   static void __meminit
> >   remove_pagetable(unsigned long start, unsigned long end, bool direct)
> >   {
> > -	unsigned long next;
> > +	unsigned long next = pgd_addr_end(start, end);
> >   	pgd_t *pgd;
> >   	pud_t *pud;
> >   	bool pgd_changed = false;
>
> This isn't enough, there's a potential for an infinite loop if
> !pgd_present() is ever true in the iteration since "next" remains
> constant.  Theoretical, maybe.
>
> I think it's better to just set next before checking for !pgd_present() in
> the iteration so it's clear what's happening.

Yes, Andrew's patch just fixed it like this. :)

Thanks. :)

> Or, even better, change
> this into the standard do-while loop that everything else uses.

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