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Commit 9476df7d authored by Dan Williams's avatar Dan Williams Committed by Linus Torvalds
Browse files

mm: introduce find_dev_pagemap() 



There are several scenarios where we need to retrieve and update
metadata associated with a given devm_memremap_pages() mapping, and the
only lookup key available is a pfn in the range:

1/ We want to augment vmemmap_populate() (called via arch_add_memory())
   to allocate memmap storage from pre-allocated pages reserved by the
   device driver.  At vmemmap_alloc_block_buf() time it grabs device pages
   rather than page allocator pages.  This is in support of
   devm_memremap_pages() mappings where the memmap is too large to fit in
   main memory (i.e. large persistent memory devices).

2/ Taking a reference against the mapping when inserting device pages
   into the address_space radix of a given inode.  This facilitates
   unmap_mapping_range() and truncate_inode_pages() operations when the
   driver is tearing down the mapping.

3/ get_user_pages() operations on ZONE_DEVICE memory require taking a
   reference against the mapping so that the driver teardown path can
   revoke and drain usage of device pages.

Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
Tested-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 260ae3f7

drivers/nvdimm/pmem.c

+1 −1
Original line number Diff line number Diff line
@@ -21,9 +21,9 @@ 
#include <linux/init.h>

#include <linux/platform_device.h>

#include <linux/module.h>

#include <linux/memory_hotplug.h>

#include <linux/moduleparam.h>

#include <linux/badblocks.h>

#include <linux/memremap.h>

#include <linux/vmalloc.h>

#include <linux/pfn_t.h>

#include <linux/slab.h>

include/linux/io.h

+0 −15
Original line number Diff line number Diff line
@@ -89,21 +89,6 @@ void devm_memunmap(struct device *dev, void *addr); 


void *__devm_memremap_pages(struct device *dev, struct resource *res);



#ifdef CONFIG_ZONE_DEVICE

void *devm_memremap_pages(struct device *dev, struct resource *res);

#else

static inline void *devm_memremap_pages(struct device *dev, struct resource *res)

{

	/*

	 * Fail attempts to call devm_memremap_pages() without

	 * ZONE_DEVICE support enabled, this requires callers to fall

	 * back to plain devm_memremap() based on config

	 */

	WARN_ON_ONCE(1);

	return ERR_PTR(-ENXIO);

}

#endif



/*

 * Some systems do not have legacy ISA devices.

 * /dev/port is not a valid interface on these systems.

include/linux/memremap.h

0 → 100644
+38 −0
Original line number Diff line number Diff line 
#ifndef _LINUX_MEMREMAP_H_

#define _LINUX_MEMREMAP_H_

#include <linux/mm.h>



struct resource;

struct device;

/**

 * struct dev_pagemap - metadata for ZONE_DEVICE mappings

 * @dev: host device of the mapping for debug

 */

struct dev_pagemap {

	/* TODO: vmem_altmap and percpu_ref count */

	struct device *dev;

};



#ifdef CONFIG_ZONE_DEVICE

void *devm_memremap_pages(struct device *dev, struct resource *res);

struct dev_pagemap *find_dev_pagemap(resource_size_t phys);

#else

static inline void *devm_memremap_pages(struct device *dev,

		struct resource *res)

{

	/*

	 * Fail attempts to call devm_memremap_pages() without

	 * ZONE_DEVICE support enabled, this requires callers to fall

	 * back to plain devm_memremap() based on config

	 */

	WARN_ON_ONCE(1);

	return ERR_PTR(-ENXIO);

}



static inline struct dev_pagemap *find_dev_pagemap(resource_size_t phys)

{

	return NULL;

}

#endif



#endif /* _LINUX_MEMREMAP_H_ */

kernel/memremap.c

+77 −8
Original line number Diff line number Diff line
@@ -10,6 +10,8 @@ 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 */

#include <linux/radix-tree.h>

#include <linux/memremap.h>

#include <linux/device.h>

#include <linux/types.h>

#include <linux/pfn_t.h>
@@ -155,22 +157,57 @@ pfn_t phys_to_pfn_t(dma_addr_t addr, unsigned long flags) 
EXPORT_SYMBOL(phys_to_pfn_t);



#ifdef CONFIG_ZONE_DEVICE

static DEFINE_MUTEX(pgmap_lock);

static RADIX_TREE(pgmap_radix, GFP_KERNEL);

#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1)

#define SECTION_SIZE (1UL << PA_SECTION_SHIFT)



struct page_map {

	struct resource res;

	struct percpu_ref *ref;

	struct dev_pagemap pgmap;

};



static void devm_memremap_pages_release(struct device *dev, void *res)

static void pgmap_radix_release(struct resource *res)

{

	struct page_map *page_map = res;

	resource_size_t key;



	mutex_lock(&pgmap_lock);

	for (key = res->start; key <= res->end; key += SECTION_SIZE)

		radix_tree_delete(&pgmap_radix, key >> PA_SECTION_SHIFT);

	mutex_unlock(&pgmap_lock);

}



static void devm_memremap_pages_release(struct device *dev, void *data)

{

	struct page_map *page_map = data;

	struct resource *res = &page_map->res;

	resource_size_t align_start, align_size;



	pgmap_radix_release(res);



	/* pages are dead and unused, undo the arch mapping */

	arch_remove_memory(page_map->res.start, resource_size(&page_map->res));

	align_start = res->start & ~(SECTION_SIZE - 1);

	align_size = ALIGN(resource_size(res), SECTION_SIZE);

	arch_remove_memory(align_start, align_size);

}



/* assumes rcu_read_lock() held at entry */

struct dev_pagemap *find_dev_pagemap(resource_size_t phys)

{

	struct page_map *page_map;



	WARN_ON_ONCE(!rcu_read_lock_held());



	page_map = radix_tree_lookup(&pgmap_radix, phys >> PA_SECTION_SHIFT);

	return page_map ? &page_map->pgmap : NULL;

}



void *devm_memremap_pages(struct device *dev, struct resource *res)

{

	int is_ram = region_intersects(res->start, resource_size(res),

			"System RAM");

	resource_size_t key, align_start, align_size;

	struct page_map *page_map;

	int error, nid;
@@ -190,18 +227,50 @@ void *devm_memremap_pages(struct device *dev, struct resource *res) 


	memcpy(&page_map->res, res, sizeof(*res));



	page_map->pgmap.dev = dev;

	mutex_lock(&pgmap_lock);

	error = 0;

	for (key = res->start; key <= res->end; key += SECTION_SIZE) {

		struct dev_pagemap *dup;



		rcu_read_lock();

		dup = find_dev_pagemap(key);

		rcu_read_unlock();

		if (dup) {

			dev_err(dev, "%s: %pr collides with mapping for %s\n",

					__func__, res, dev_name(dup->dev));

			error = -EBUSY;

			break;

		}

		error = radix_tree_insert(&pgmap_radix, key >> PA_SECTION_SHIFT,

				page_map);

		if (error) {

			dev_err(dev, "%s: failed: %d\n", __func__, error);

			break;

		}

	}

	mutex_unlock(&pgmap_lock);

	if (error)

		goto err_radix;



	nid = dev_to_node(dev);

	if (nid < 0)

		nid = numa_mem_id();



	error = arch_add_memory(nid, res->start, resource_size(res), true);

	if (error) {

		devres_free(page_map);

		return ERR_PTR(error);

	}

	align_start = res->start & ~(SECTION_SIZE - 1);

	align_size = ALIGN(resource_size(res), SECTION_SIZE);

	error = arch_add_memory(nid, align_start, align_size, true);

	if (error)

		goto err_add_memory;



	devres_add(dev, page_map);

	return __va(res->start);



 err_add_memory:

 err_radix:

	pgmap_radix_release(res);

	devres_free(page_map);

	return ERR_PTR(error);

}

EXPORT_SYMBOL(devm_memremap_pages);

#endif /* CONFIG_ZONE_DEVICE */