On Mon, May 11, 2026 at 05:03:41AM -0400, Michael S. Tsirkin wrote: > Propagate PG_zeroed through buddy splits in page_del_and_expand() > and try_to_claim_block(). When a zeroed high-order page is split > to satisfy a smaller allocation, the sub-pages placed back on the > free lists keep PG_zeroed. > > Signed-off-by: Michael S. Tsirkin <[email protected]> > Assisted-by: Claude:claude-opus-4-6 > Assisted-by: cursor-agent:GPT-5.4-xhigh
Reviewed-by: Gregory Price <[email protected]> > --- > mm/page_alloc.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d70c9ba6b329..468e8bde7d34 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1712,7 +1712,8 @@ struct page *__pageblock_pfn_to_page(unsigned long > start_pfn, > * -- nyc > */ > static inline unsigned int expand(struct zone *zone, struct page *page, int > low, > - int high, int migratetype, bool reported) > + int high, int migratetype, bool reported, > + bool zeroed) > { > unsigned int size = 1 << high; > unsigned int nr_added = 0; > @@ -1743,6 +1744,8 @@ static inline unsigned int expand(struct zone *zone, > struct page *page, int low, > */ > if (reported) > __SetPageReported(&page[size]); > + if (zeroed) > + __SetPageZeroed(&page[size]); > } > > return nr_added; > @@ -1754,10 +1757,12 @@ static __always_inline void > page_del_and_expand(struct zone *zone, > { > int nr_pages = 1 << high; > bool was_reported = page_reported(page); > + bool was_zeroed = PageZeroed(page); > > __del_page_from_free_list(page, zone, high, migratetype); > > - nr_pages -= expand(zone, page, low, high, migratetype, was_reported); > + nr_pages -= expand(zone, page, low, high, migratetype, was_reported, > + was_zeroed); > account_freepages(zone, -nr_pages, migratetype); > } > > @@ -2335,11 +2340,12 @@ try_to_claim_block(struct zone *zone, struct page > *page, > if (current_order >= pageblock_order) { > unsigned int nr_added; > bool was_reported = page_reported(page); > + bool was_zeroed = PageZeroed(page); > > del_page_from_free_list(page, zone, current_order, block_type); > change_pageblock_range(page, current_order, start_type); > nr_added = expand(zone, page, order, current_order, start_type, > - was_reported); > + was_reported, was_zeroed); > account_freepages(zone, nr_added, start_type); > return page; > } > -- > MST >
