Move prep_compound_page() before post_alloc_hook() in prep_new_page(). The next patch adds a folio_zero_user() call to post_alloc_hook(), which uses folio_nr_pages() to determine how many pages to zero. Without compound metadata set up first, folio_nr_pages() returns 1 for higher-order allocations, so only the first page would be zeroed.
All other operations in post_alloc_hook() (arch_alloc_page, KASAN, debug, page owner, etc.) use raw page pointers with explicit order counts and are unaffected by this reordering. Also reorder compaction_alloc_noprof() for consistency. Compaction currently passes USER_ADDR_NONE so folio_zero_user() is not called there, but keeping the same ordering avoids a future tripping hazard. Reviewed-by: Gregory Price <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]> Assisted-by: Claude:claude-opus-4-6 Assisted-by: cursor-agent:GPT-5.4-xhigh --- mm/compaction.c | 4 ++-- mm/page_alloc.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 72684fe81e83..4336e433c99b 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1849,10 +1849,10 @@ static struct folio *compaction_alloc_noprof(struct folio *src, unsigned long da set_page_private(&freepage[size], start_order); } dst = (struct folio *)freepage; - post_alloc_hook(&dst->page, order, __GFP_MOVABLE, USER_ADDR_NONE); - set_page_refcounted(&dst->page); if (order) prep_compound_page(&dst->page, order); + post_alloc_hook(&dst->page, order, __GFP_MOVABLE, USER_ADDR_NONE); + set_page_refcounted(&dst->page); cc->nr_freepages -= 1 << order; cc->nr_migratepages -= 1 << order; return page_rmappable_folio(&dst->page); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8c673095c11f..db387dd6b813 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1874,11 +1874,11 @@ static void prep_new_page(struct page *page, unsigned int order, gfp_t gfp_flags unsigned int alloc_flags, unsigned long user_addr) { - post_alloc_hook(page, order, gfp_flags, user_addr); - if (order && (gfp_flags & __GFP_COMP)) prep_compound_page(page, order); + post_alloc_hook(page, order, gfp_flags, user_addr); + /* * page is set pfmemalloc when ALLOC_NO_WATERMARKS was necessary to * allocate the page. The expectation is that the caller is taking -- MST
