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

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Date:   Wed, 12 May 2021 05:01:01 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...nel.org>
Cc:     linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        sparclinux@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v2 4/5] mm/vmalloc: Enable mapping of huge pages at pte level
 in vmalloc

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@...roup.eu>
---
 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