On Thu, 2014-07-24 at 08:45 -0400, Naoya Horiguchi wrote: > Hi Zhong, > > On Thu, Jul 24, 2014 at 05:36:25PM +0800, Li Zhong wrote: > > It is possible for some platforms, such as powerpc to set HPAGE_SHIFT to > > 0 to indicate huge pages not supported. > > > > When this is the case, hugetlbfs could be disabled during boot time: > > hugetlbfs: disabling because there are no supported hugepage sizes > > > > Then in dissolve_free_huge_pages(), order is kept maximum (64 for > > 64bits), and the for loop below won't end: > > for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) > > At first I wonder that why could dissolve_free_huge_pages() is called > if the platform doesn't support hugetlbfs. But I found that the function > is called by memory hotplug code without checking hugepage support. > > So it looks to me straightforward and self-descriptive to check > hugepage_supported() just before calling dissolve_free_huge_pages(). Hi, Naoya, Thank you for the review and suggestion. I'll send a updated version. Thanks, Zhong > > Thanks, > Naoya Horiguchi > > > The fix below returns directly if the order isn't set to a correct > > value. > > > > Signed-off-by: Li Zhong <zhong@xxxxxxxxxxxxxxxxxx> > > --- > > mm/hugetlb.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > > index 2024bbd..a950817 100644 > > --- a/mm/hugetlb.c > > +++ b/mm/hugetlb.c > > @@ -1093,6 +1093,10 @@ void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn) > > for_each_hstate(h) > > if (order > huge_page_order(h)) > > order = huge_page_order(h); > > + > > + if (order == 8 * sizeof(void *)) > > + return; > > + > > VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order)); > > for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) > > dissolve_free_huge_page(pfn_to_page(pfn)); > > > > > > -- > > To unsubscribe, send a message with 'unsubscribe linux-mm' in > > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > > see: http://www.linux-mm.org/ . > > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>