folio_zero_user() is defined in mm/memory.c under CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS. A subsequent patch will call it from post_alloc_hook() for all user page zeroing, so configs without THP or HUGETLBFS will need a stub.
Add a stub that uses clear_user_highpages() with aligned addr_hint. Without THP/HUGETLBFS, only order-0 user pages are allocated, so the locality optimization in the real folio_zero_user() (zero near the faulting address last) is not needed. This also matches what vma_alloc_zeroed_movable_folio currently does. Signed-off-by: Michael S. Tsirkin <[email protected]> Assisted-by: Claude:claude-opus-4-6 Assisted-by: cursor-agent:GPT-5.4-xhigh --- include/linux/mm.h | 2 ++ mm/memory.c | 9 +++++++++ 2 files changed, 11 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index af23453e9dbd..d1e768dcda13 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -5070,6 +5070,8 @@ long copy_folio_from_user(struct folio *dst_folio, const void __user *usr_src, bool allow_pagefault); +#else /* !CONFIG_TRANSPARENT_HUGEPAGE && !CONFIG_HUGETLBFS */ +void folio_zero_user(struct folio *folio, unsigned long addr_hint); #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #if MAX_NUMNODES > 1 diff --git a/mm/memory.c b/mm/memory.c index ea6568571131..02d3e53fc91b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -7546,6 +7546,15 @@ long copy_folio_from_user(struct folio *dst_folio, } #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ +#if !defined(CONFIG_TRANSPARENT_HUGEPAGE) && !defined(CONFIG_HUGETLBFS) +void folio_zero_user(struct folio *folio, unsigned long addr_hint) +{ + unsigned long base = ALIGN_DOWN(addr_hint, folio_size(folio)); + + clear_user_highpages(&folio->page, base, folio_nr_pages(folio)); +} +#endif + #if defined(CONFIG_SPLIT_PTE_PTLOCKS) && ALLOC_SPLIT_PTLOCKS static struct kmem_cache *page_ptl_cachep; -- MST
