[PATCH v2 4/5] mm/vmalloc: Enable mapping of huge pages at pte level in vmalloc

[Christophe Leroy <christophe.leroy@xxxxxxxxxx>]

On some architectures like powerpc, there are huge pages that
are mapped at pte level.

Enable it in vmalloc.

For that, architectures can provide arch_vmap_pte_supported_shift()
that returns the shift for pages to map at pte level.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 include/linux/vmalloc.h |  7 +++++++
 mm/vmalloc.c            | 13 +++++++------
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 13c9b19ec923..bf0a1b7a824e 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -112,6 +112,13 @@ static inline unsigned long arch_vmap_pte_range_map_size(unsigned long addr, uns
 }
 #endif
 
+#ifndef arch_vmap_pte_supported_shift
+static inline int arch_vmap_pte_supported_shift(unsigned long size)
+{
+	return PAGE_SHIFT;
+}
+#endif
+
 /*
  *	Highlevel APIs for driver use
  */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 783d23b8c2f7..3de5291c20cd 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2895,8 +2895,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
 		return NULL;
 	}
 
-	if (vmap_allow_huge && !(vm_flags & VM_NO_HUGE_VMAP) &&
-			arch_vmap_pmd_supported(prot)) {
+	if (vmap_allow_huge && !(vm_flags & VM_NO_HUGE_VMAP)) {
 		unsigned long size_per_node;
 
 		/*
@@ -2909,11 +2908,13 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
 		size_per_node = size;
 		if (node == NUMA_NO_NODE)
 			size_per_node /= num_online_nodes();
-		if (size_per_node >= PMD_SIZE) {
+		if (arch_vmap_pmd_supported(prot) && size_per_node >= PMD_SIZE)
 			shift = PMD_SHIFT;
-			align = max(real_align, 1UL << shift);
-			size = ALIGN(real_size, 1UL << shift);
-		}
+		else
+			shift = arch_vmap_pte_supported_shift(size_per_node);
+
+		align = max(real_align, 1UL << shift);
+		size = ALIGN(real_size, 1UL << shift);
 	}
 
 again:
-- 
2.25.0