On 08/30/23 16:33, Muchun Song wrote:
>
>
> On 2023/8/26 03:04, Mike Kravetz wrote:
> > When removing hugetlb pages from the pool, we first create a list
> > of removed pages and then free those pages back to low level allocators.
> > Part of the 'freeing process' is to restore vmemmap for all base pages
> > if necessary. Pass this list of pages to a new routine
> > hugetlb_vmemmap_restore_folios() so that vmemmap restoration can be
> > performed in bulk.
> >
> > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
> > ---
> > mm/hugetlb.c | 3 +++
> > mm/hugetlb_vmemmap.c | 8 ++++++++
> > mm/hugetlb_vmemmap.h | 6 ++++++
> > 3 files changed, 17 insertions(+)
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 3133dbd89696..1bde5e234d5c 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1833,6 +1833,9 @@ static void update_and_free_pages_bulk(struct hstate *h, struct list_head *list)
> > {
> > struct folio *folio, *t_folio;
> > + /* First restore vmemmap for all pages on list. */
> > + hugetlb_vmemmap_restore_folios(h, list);
> > +
> > list_for_each_entry_safe(folio, t_folio, list, lru) {
> > update_and_free_hugetlb_folio(h, folio, false);
> > cond_resched();
> > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
> > index 147018a504a6..d5e6b6c76dce 100644
> > --- a/mm/hugetlb_vmemmap.c
> > +++ b/mm/hugetlb_vmemmap.c
> > @@ -479,6 +479,14 @@ int hugetlb_vmemmap_restore(const struct hstate *h, struct page *head)
> > return ret;
> > }
>
> Because it is a void function, I'd like to add a comment here like:
>
> This function only tries to restore a list of folios' vmemmap pages and
> does not guarantee that the restoration will succeed after it returns.
Will do. Thanks!
--
Mike Kravetz
