Hi Hillf,
On Sat, Feb 23, 2013 at 03:05:30PM +0800, Hillf Danton wrote:
> Hello Naoya
>
> [add Michal in cc list]
>
> On Fri, Feb 22, 2013 at 3:41 AM, Naoya Horiguchi
> <n-horiguchi@xxxxxxxxxxxxx> wrote:
> >
> > +/* Returns true for head pages of in-use hugepages, otherwise returns false. */
> > +int is_hugepage_movable(struct page *hpage)
> s/int/bool/ can we?
Yes, we can. I'll do this.
> > +{
> > + struct page *page;
> > + struct page *tmp;
> > + struct hstate *h = page_hstate(hpage);
> Make sense to compute hstate for a tail page?
No need to do this here.
It's better to put it after PageTail check.
> > + int ret = 0;
> > +
> > + VM_BUG_ON(!PageHuge(hpage));
> > + if (PageTail(hpage))
> > + return 0;
> VM_BUG_ON(!PageHuge(hpage) || PageTail(hpage)), can we?
I think that firing BUG_ON() for tail pages is overkill.
Pfn range over which scan_movable_pages() runs could start
at the pfn inside the hugepage when we try to hot-remove
the memory block used by 1GB hugepage. In that case,
is_hugepage_movable() can be called for tail pages as a
normal behavior.
But anyway, I'll add the comment for this corner case.
> > + spin_lock(&hugetlb_lock);
> > + list_for_each_entry_safe(page, tmp, &h->hugepage_activelist, lru)
> s/_safe// can we?
OK.
> > + if (page == hpage)
> > + ret = 1;
> Can we bail out with ret set to be true?
Yes, inserting break is good for performance.
> > + spin_unlock(&hugetlb_lock);
> > + return ret;
> > +}
Thank you!
Naoya
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