[dm-devel] [PATCH 4/7] dm: introduce dm_kvmalloc

[Mikulas Patocka]

Introduce the functions dm_kvmalloc and dm_kvmalloc_node. These functions
attempt to do allocation with kmalloc and if it fails, use vmalloc. Memory
allocated with these functions should be freed with kvfree (that function
is already present in the Linux kernel).

Signed-off-by: Mikulas Patocka <mpatocka at redhat.com>

---
 drivers/md/dm-ioctl.c         |   26 +++++---------------------
 drivers/md/dm-table.c         |   37 +++++++++++++++++++++++++++++++++++++
 include/linux/device-mapper.h |    2 ++
 3 files changed, 44 insertions(+), 21 deletions(-)

Index: linux-4.1/drivers/md/dm-ioctl.c
===================================================================
--- linux-4.1.orig/drivers/md/dm-ioctl.c	2015-07-02 19:21:15.000000000 +0200
+++ linux-4.1/drivers/md/dm-ioctl.c	2015-07-02 19:21:21.000000000 +0200
@@ -1676,12 +1676,8 @@ static void free_params(struct dm_ioctl 
 	if (param_flags & DM_WIPE_BUFFER)
 		memset(param, 0, param_size);
 
-	if (param_flags & DM_PARAMS_ALLOC) {
-		if (is_vmalloc_addr(param))
-			vfree(param);
-		else
-			kfree(param);
-	}
+	if (param_flags & DM_PARAMS_ALLOC)
+		kvfree(param);
 }
 
 static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
@@ -1712,21 +1708,7 @@ static int copy_params(struct dm_ioctl _
 	 * Try to avoid low memory issues when a device is suspended.
 	 * Use kmalloc() rather than vmalloc() when we can.
 	 */
-	dmi = NULL;
-	if (param_kernel->data_size <= KMALLOC_MAX_SIZE) {
-		dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
-		if (dmi)
-			*param_flags |= DM_PARAMS_ALLOC;
-	}
-
-	if (!dmi) {
-		unsigned noio_flag;
-		noio_flag = memalloc_noio_save();
-		dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
-		memalloc_noio_restore(noio_flag);
-		if (dmi)
-			*param_flags |= DM_PARAMS_ALLOC;
-	}
+	dmi = dm_kvmalloc(param_kernel->data_size, GFP_NOIO);
 
 	if (!dmi) {
 		if (secure_data && clear_user(user, param_kernel->data_size))
@@ -1734,6 +1716,8 @@ static int copy_params(struct dm_ioctl _
 		return -ENOMEM;
 	}
 
+	*param_flags |= DM_PARAMS_ALLOC;
+
 	if (copy_from_user(dmi, user, param_kernel->data_size))
 		goto bad;
 
Index: linux-4.1/include/linux/device-mapper.h
===================================================================
--- linux-4.1.orig/include/linux/device-mapper.h	2015-07-02 19:21:16.000000000 +0200
+++ linux-4.1/include/linux/device-mapper.h	2015-07-02 19:21:21.000000000 +0200
@@ -475,6 +475,8 @@ struct dm_table *dm_swap_table(struct ma
 /*
  * A wrapper around vmalloc.
  */
+void *dm_kvmalloc_node(size_t size, gfp_t gfp, int node);
+void *dm_kvmalloc(size_t size, gfp_t gfp);
 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
 
 /*-----------------------------------------------------------------
Index: linux-4.1/drivers/md/dm-table.c
===================================================================
--- linux-4.1.orig/drivers/md/dm-table.c	2015-07-02 19:21:16.000000000 +0200
+++ linux-4.1/drivers/md/dm-table.c	2015-07-02 19:28:18.000000000 +0200
@@ -131,6 +131,43 @@ static int setup_btree_index(unsigned in
 	return 0;
 }
 
+void *dm_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(dm_kvmalloc_node);
+
+void *dm_kvmalloc(size_t size, gfp_t gfp)
+{
+	return dm_kvmalloc_node(size, gfp, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(dm_kvmalloc);
+
 void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size)
 {
 	unsigned long size;