If the VM_HUGEPAGE flag is set, attempt to allocate PMD-sized folios
during readahead, even if we have no history of readahead being
successful.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/filemap.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index fe764225ae99..7608ee030662 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2995,6 +2995,24 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
struct file *fpin = NULL;
unsigned int mmap_miss;
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+ /* Use the readahead code, even if readahead is disabled */
+ if (vmf->vma->vm_flags & VM_HUGEPAGE) {
+ fpin = maybe_unlock_mmap_for_io(vmf, fpin);
+ ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1);
+ ra->size = HPAGE_PMD_NR;
+ /*
+ * Fetch two PMD folios, so we get the chance to actually
+ * readahead, unless we've been told not to.
+ */
+ if (!(vmf->vma->vm_flags & VM_RAND_READ))
+ ra->size *= 2;
+ ra->async_size = HPAGE_PMD_NR;
+ page_cache_ra_order(&ractl, ra, HPAGE_PMD_ORDER);
+ return fpin;
+ }
+#endif
+
/* If we don't want any read-ahead, don't bother */
if (vmf->vma->vm_flags & VM_RAND_READ)
return fpin;
--
2.34.1
