> Now that gigantic pages are dynamically allocatable, care must be taken > to ensure that p->first_page is valid before setting PageTail. > > If this isn't done, then it is possible to race and have compound_head() > return NULL. > > Signed-off-by: David Rientjes <rient...@google.com> > --- Acked-by: Hillf Danton <hillf...@alibaba-inc.com>
> mm/hugetlb.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -917,7 +917,6 @@ static void prep_compound_gigantic_page(struct page > *page, unsigned long order) > __SetPageHead(page); > __ClearPageReserved(page); > for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { > - __SetPageTail(p); > /* > * For gigantic hugepages allocated through bootmem at > * boot, it's safer to be consistent with the not-gigantic > @@ -933,6 +932,9 @@ static void prep_compound_gigantic_page(struct page > *page, unsigned long order) > __ClearPageReserved(p); > set_page_count(p, 0); > p->first_page = page; > + /* Make sure p->first_page is always valid for PageTail() */ > + smp_wmb(); > + __SetPageTail(p); > } > } > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/