Like vma_alloc_zeroed_movable_folio(), except it will opportunistically
attempt to allocate high-order folios, retrying with lower orders all
the way to order-0, until success. 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 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 | 27 ++++++++++++++++++++++++---
1 file changed, 24 insertions(+), 3 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c
index 8798da968686..c9e09415ee18 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3024,6 +3024,27 @@ static inline void wp_page_reuse(struct vm_fault *vmf)
count_vm_event(PGREUSE);
}
+/*
+ * Opportunistically attempt to allocate high-order folios, retrying with lower
+ * orders all the way to order-0, until success. The user must check what they
+ * got with folio_order().
+ */
+static struct folio *try_vma_alloc_zeroed_movable_folio(
+ struct vm_area_struct *vma,
+ unsigned long vaddr, int order)
+{
+ struct folio *folio;
+ gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
+
+ for (; order > 0; order--) {
+ folio = vma_alloc_zeroed_movable_folio(vma, vaddr, gfp, order);
+ if (folio)
+ return folio;
+ }
+
+ return vma_alloc_zeroed_movable_folio(vma, vaddr, 0, 0);
+}
+
/*
* Handle the case of a page which we actually need to copy to a new page,
* either due to COW or unsharing.
@@ -3061,8 +3082,8 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
goto oom;
if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
- new_folio = vma_alloc_zeroed_movable_folio(vma, vmf->address,
- 0, 0);
+ new_folio = try_vma_alloc_zeroed_movable_folio(vma,
+ vmf->address, 0);
if (!new_folio)
goto oom;
} else {
@@ -4050,7 +4071,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
/* Allocate our own private page. */
if (unlikely(anon_vma_prepare(vma)))
goto oom;
- folio = vma_alloc_zeroed_movable_folio(vma, vmf->address, 0, 0);
+ folio = try_vma_alloc_zeroed_movable_folio(vma, vmf->address, 0);
if (!folio)
goto oom;
--
2.25.1
