On Mon, Jun 26, 2023 at 8:34 PM Yu Zhao <yuzhao@xxxxxxxxxx> wrote:
On Mon, Jun 26, 2023 at 11:14 AM Ryan Roberts <ryan.roberts@xxxxxxx> wrote:Opportunistically attempt to allocate high-order folios in highmem, optionally zeroed. Retry with lower orders all the way to order-0, until success. Although, of note, order-1 allocations are skipped since a large folio must be at least order-2 to work with the THP machinery. The user must check what they got with folio_order(). This will be used to oportunistically allocate large folios for anonymous memory with a sensible fallback under memory pressure. For attempts to allocate non-0 orders, we set __GFP_NORETRY to prevent high latency due to reclaim, instead preferring to just try for a lower order. The same approach is used by the readahead code when allocating large folios. Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- mm/memory.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 367bbbb29d91..53896d46e686 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3001,6 +3001,39 @@ static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf) return 0; } +static inline struct folio *vma_alloc_movable_folio(struct vm_area_struct *vma, + unsigned long vaddr, int order, bool zeroed) +{ + gfp_t gfp = order > 0 ? __GFP_NORETRY | __GFP_NOWARN : 0; + + if (zeroed) + return vma_alloc_zeroed_movable_folio(vma, vaddr, gfp, order); + else + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | gfp, order, vma, + vaddr, false); +} + +/* + * Opportunistically attempt to allocate high-order folios, retrying with lower + * orders all the way to order-0, until success. order-1 allocations are skipped + * since a folio must be at least order-2 to work with the THP machinery. The + * user must check what they got with folio_order(). vaddr can be any virtual + * address that will be mapped by the allocated folio. + */ +static struct folio *try_vma_alloc_movable_folio(struct vm_area_struct *vma, + unsigned long vaddr, int order, bool zeroed) +{ + struct folio *folio; + + for (; order > 1; order--) { + folio = vma_alloc_movable_folio(vma, vaddr, order, zeroed); + if (folio) + return folio; + } + + return vma_alloc_movable_folio(vma, vaddr, 0, zeroed); +}I'd drop this patch. Instead, in do_anonymous_page(): if (IS_ENABLED(CONFIG_ARCH_WANTS_PTE_ORDER)) folio = vma_alloc_zeroed_movable_folio(vma, addr, CONFIG_ARCH_WANTS_PTE_ORDER)) if (!folio) folio = vma_alloc_zeroed_movable_folio(vma, addr, 0);
I meant a runtime function arch_wants_pte_order() (Its default implementation would return 0.)
