[PATCH 2/7] mm: introduce kvmalloc and kvmalloc_node

[Mikulas Patocka]

Introduce the functions kvmalloc and kvmalloc_node. These functions
provide reliable allocation of object of arbitrary size. They attempt to
do allocation with kmalloc and if it fails, use vmalloc. Memory allocated
with these functions should be freed with kvfree.

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>

---
 include/linux/mm.h |    2 ++
 mm/util.c          |   37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

Index: linux-4.2-rc1/include/linux/mm.h
===================================================================
--- linux-4.2-rc1.orig/include/linux/mm.h	2015-07-07 15:54:36.000000000 +0200
+++ linux-4.2-rc1/include/linux/mm.h	2015-07-07 15:54:58.000000000 +0200
@@ -400,6 +400,8 @@ static inline int is_vmalloc_or_module_a
 }
 #endif
 
+extern void *kvmalloc_node(size_t size, gfp_t gfp, int node);
+extern void *kvmalloc(size_t size, gfp_t gfp);
 extern void kvfree(const void *addr);
 
 static inline void compound_lock(struct page *page)
Index: linux-4.2-rc1/mm/util.c
===================================================================
--- linux-4.2-rc1.orig/mm/util.c	2015-07-07 15:52:37.000000000 +0200
+++ linux-4.2-rc1/mm/util.c	2015-07-07 15:54:06.000000000 +0200
@@ -316,6 +316,43 @@ unsigned long vm_mmap(struct file *file,
 }
 EXPORT_SYMBOL(vm_mmap);
 
+void *kvmalloc_node(size_t size, gfp_t gfp, int node)
+{
+	void *p;
+	unsigned uninitialized_var(noio_flag);
+
+	/* vmalloc doesn't support no-wait allocations */
+	WARN_ON(!(gfp & __GFP_WAIT));
+
+	if (likely(size <= KMALLOC_MAX_SIZE)) {
+		p = kmalloc_node(size, gfp | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN, node);
+		if (likely(p != NULL))
+			return p;
+	}
+	if ((gfp & (__GFP_IO | __GFP_FS)) != (__GFP_IO | __GFP_FS)) {
+		/*
+		 * vmalloc allocates page tables with GFP_KERNEL, regardless
+		 * of GFP flags passed to it. If we are no GFP_NOIO context,
+		 * we call memalloc_noio_save, so that all allocations are
+		 * implicitly done with GFP_NOIO.
+		 */
+		noio_flag = memalloc_noio_save();
+		gfp |= __GFP_HIGH;
+	}
+	p = __vmalloc_node_flags(size, node, gfp | __GFP_REPEAT | __GFP_HIGHMEM);
+	if ((gfp & (__GFP_IO | __GFP_FS)) != (__GFP_IO | __GFP_FS)) {
+		memalloc_noio_restore(noio_flag);
+	}
+	return p;
+}
+EXPORT_SYMBOL(kvmalloc_node);
+
+void *kvmalloc(size_t size, gfp_t gfp)
+{
+	return kvmalloc_node(size, gfp, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(kvmalloc);
+
 void kvfree(const void *addr)
 {
 	if (is_vmalloc_addr(addr))

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