[PATCH bpf 2/4] vmalloc: introduce HAVE_ARCH_HUGE_VMALLOC_FLAG

[Song Liu <song@kernel.org>]

With HAVE_ARCH_HUGE_VMALLOC_FLAG, users of __vmalloc_node_range() could
use VM_TRY_HUGE_VMAP to (try to) allocate PMD_SIZE pages for
size >= PMD_SIZE cases. Similar to HAVE_ARCH_HUGE_VMALLOC, the use can
disable huge page by specifying nohugeiomap in kernel command line.

The first user of VM_TRY_HUGE_VMAP will be bpf_prog_pack.

Signed-off-by: Song Liu <song@kernel.org>
---
 arch/Kconfig            |  9 +++++++++
 include/linux/vmalloc.h |  9 +++++++--
 mm/vmalloc.c            | 28 +++++++++++++++++++---------
 3 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 33e06966f248..23b6e92aebaa 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -864,6 +864,15 @@ config HAVE_ARCH_HUGE_VMALLOC
 	depends on HAVE_ARCH_HUGE_VMAP
 	bool
 
+#
+# HAVE_ARCH_HUGE_VMALLOC_FLAG allows users of __vmalloc_node_range to allocate
+# huge page without HAVE_ARCH_HUGE_VMALLOC. To allocate huge pages, the user
+# need to call __vmalloc_node_range with VM_TRY_HUGE_VMAP.
+#
+config HAVE_ARCH_HUGE_VMALLOC_FLAG
+	depends on HAVE_ARCH_HUGE_VMAP
+	bool
+
 config ARCH_WANT_HUGE_PMD_SHARE
 	bool
 
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 3b1df7da402d..a48d0690b66f 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -35,6 +35,11 @@ struct notifier_block;		/* in notifier.h */
 #define VM_DEFER_KMEMLEAK	0
 #endif
 
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG
+#define VM_TRY_HUGE_VMAP	0x00001000	/* Allow for huge pages on HAVE_ARCH_HUGE_VMALLOC_FLAG arch's */
+#else
+#define VM_TRY_HUGE_VMAP	0
+#endif
 /* bits [20..32] reserved for arch specific ioremap internals */
 
 /*
@@ -51,7 +56,7 @@ struct vm_struct {
 	unsigned long		size;
 	unsigned long		flags;
 	struct page		**pages;
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
+#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
 	unsigned int		page_order;
 #endif
 	unsigned int		nr_pages;
@@ -225,7 +230,7 @@ static inline bool is_vm_area_hugepages(const void *addr)
 	 * prevents that. This only indicates the size of the physical page
 	 * allocated in the vmalloc layer.
 	 */
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
+#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
 	return find_vm_area(addr)->page_order > 0;
 #else
 	return false;
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e163372d3967..179200bce285 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -46,7 +46,7 @@
 #include "internal.h"
 #include "pgalloc-track.h"
 
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
 static unsigned int __ro_after_init ioremap_max_page_shift = BITS_PER_LONG - 1;
 
 static int __init set_nohugeiomap(char *str)
@@ -55,11 +55,11 @@ static int __init set_nohugeiomap(char *str)
 	return 0;
 }
 early_param("nohugeiomap", set_nohugeiomap);
-#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
+#else /* CONFIG_HAVE_ARCH_HUGE_VMAP || CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG */
 static const unsigned int ioremap_max_page_shift = PAGE_SHIFT;
-#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
+#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP || CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG*/
 
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
+#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
 static bool __ro_after_init vmap_allow_huge = true;
 
 static int __init set_nohugevmalloc(char *str)
@@ -582,8 +582,9 @@ int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 
 	WARN_ON(page_shift < PAGE_SHIFT);
 
-	if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
-			page_shift == PAGE_SHIFT)
+	if ((!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) &&
+	     !IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG)) ||
+	    (page_shift == PAGE_SHIFT))
 		return vmap_small_pages_range_noflush(addr, end, prot, pages);
 
 	for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) {
@@ -2252,7 +2253,7 @@ static struct vm_struct *vmlist __initdata;
 
 static inline unsigned int vm_area_page_order(struct vm_struct *vm)
 {
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
+#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
 	return vm->page_order;
 #else
 	return 0;
@@ -2261,7 +2262,7 @@ static inline unsigned int vm_area_page_order(struct vm_struct *vm)
 
 static inline void set_vm_area_page_order(struct vm_struct *vm, unsigned int order)
 {
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
+#if (defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || defined(CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG))
 	vm->page_order = order;
 #else
 	BUG_ON(order != 0);
@@ -3056,6 +3057,15 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	return NULL;
 }
 
+static bool vmalloc_try_huge_page(unsigned long vm_flags)
+{
+	if (!vmap_allow_huge || (vm_flags & VM_NO_HUGE_VMAP))
+		return false;
+
+	/* VM_TRY_HUGE_VMAP only works for CONFIG_HAVE_ARCH_HUGE_VMALLOC_FLAG */
+	return vm_flags & VM_TRY_HUGE_VMAP;
+}
+
 /**
  * __vmalloc_node_range - allocate virtually contiguous memory
  * @size:		  allocation size
@@ -3106,7 +3116,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
 		return NULL;
 	}
 
-	if (vmap_allow_huge && !(vm_flags & VM_NO_HUGE_VMAP)) {
+	if (vmalloc_try_huge_page(vm_flags)) {
 		unsigned long size_per_node;
 
 		/*
-- 
2.30.2