RE: hugetlb demand paging patch part [3/3]

From: Chen, Kenneth W <kenneth.w.chen_at_intel.com>
Date: 2004-04-16 03:16:45
>>>>> David Gibson wrote on Thursday, April 15, 2004 12:26 AM
>
> > @@ -175,7 +132,6 @@ struct page *follow_huge_addr(struct mm_
> >  		return NULL;
> >  	page = pte_page(*ptep);
> >  	page += ((addr & ~HPAGE_MASK) >> PAGE_SHIFT);
> > -	get_page(page);
> >  	return page;
> >  }
>
> As far as I can tell, the removal of these get_page()s is also
> unrelated to the demand paging per se.  But afaict removing them is
> correct - the corresponding logic in follow_page() for normal pages
> doesn't appear to do a get_page(), nor do all archs do a get_page().
>
> Does that sound right to you?

It's a bug in the code that was never exercised with prefaulting.  See
get_user_pages() that short circuits the rest of faulting code with
is_vm_hugetlb_page() test.


> If so, the patch below ought to be safe (and indeed a bugfix) to
> apply now:

Yep, that's correct, I already did x86 and ia64 in one of the three
patches posted. ;-)


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Received on Thu Apr 15 13:23:18 2004

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