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Commit fbbb7f4e authored by Tejun Heo's avatar Tejun Heo
Browse files

percpu: remove the usage of separate populated bitmap in percpu-vm 



percpu-vm uses pcpu_get_pages_and_bitmap() to acquire temp pages array
and populated bitmap and uses the two during [de]population.  The temp
bitmap is used only to build the new bitmap that is copied to
chunk->populated after the operation succeeds; however, the new bitmap
can be trivially set after success without using the temp bitmap.

This patch removes the temp populated bitmap usage from percpu-vm.c.

* pcpu_get_pages_and_bitmap() is renamed to pcpu_get_pages() and no
  longer hands out the temp bitmap.

* @populated arugment is dropped from all the related functions.
  @populated updates in pcpu_[un]map_pages() are dropped.

* Two loops in pcpu_map_pages() are merged.

* pcpu_[de]populated_chunk() modify chunk->populated bitmap directly
  from @page_start and @page_end after success.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
parent 3189eddb

mm/percpu-vm.c

+25 −68
Original line number Diff line number Diff line
@@ -20,46 +20,24 @@ static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk, 
}



/**

 * pcpu_get_pages_and_bitmap - get temp pages array and bitmap

 * pcpu_get_pages - get temp pages array

 * @chunk: chunk of interest

 * @bitmapp: output parameter for bitmap

 * @may_alloc: may allocate the array

 *

 * Returns pointer to array of pointers to struct page and bitmap,

 * both of which can be indexed with pcpu_page_idx().  The returned

 * array is cleared to zero and *@bitmapp is copied from

 * @chunk->populated.  Note that there is only one array and bitmap

 * and access exclusion is the caller's responsibility.

 *

 * CONTEXT:

 * pcpu_alloc_mutex and does GFP_KERNEL allocation if @may_alloc.

 * Otherwise, don't care.

 * Returns pointer to array of pointers to struct page which can be indexed

 * with pcpu_page_idx().  Note that there is only one array and access

 * exclusion is the caller's responsibility.

 *

 * RETURNS:

 * Pointer to temp pages array on success, NULL on failure.

 * Pointer to temp pages array on success.

 */

static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk,

					       unsigned long **bitmapp,

					       bool may_alloc)

static struct page **pcpu_get_pages(struct pcpu_chunk *chunk, bool may_alloc)

{

	static struct page **pages;

	static unsigned long *bitmap;

	size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);

	size_t bitmap_size = BITS_TO_LONGS(pcpu_unit_pages) *

			     sizeof(unsigned long);



	if (!pages || !bitmap) {

		if (may_alloc && !pages)

	if (!pages && may_alloc)

		pages = pcpu_mem_zalloc(pages_size);

		if (may_alloc && !bitmap)

			bitmap = pcpu_mem_zalloc(bitmap_size);

		if (!pages || !bitmap)

			return NULL;

	}



	bitmap_copy(bitmap, chunk->populated, pcpu_unit_pages);



	*bitmapp = bitmap;

	return pages;

}
@@ -67,7 +45,6 @@ static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk, 
 * pcpu_free_pages - free pages which were allocated for @chunk

 * @chunk: chunk pages were allocated for

 * @pages: array of pages to be freed, indexed by pcpu_page_idx()

 * @populated: populated bitmap

 * @page_start: page index of the first page to be freed

 * @page_end: page index of the last page to be freed + 1

 *
@@ -75,8 +52,7 @@ static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk, 
 * The pages were allocated for @chunk.

 */

static void pcpu_free_pages(struct pcpu_chunk *chunk,

			    struct page **pages, unsigned long *populated,

			    int page_start, int page_end)

			    struct page **pages, int page_start, int page_end)

{

	unsigned int cpu;

	int i;
@@ -95,7 +71,6 @@ static void pcpu_free_pages(struct pcpu_chunk *chunk, 
 * pcpu_alloc_pages - allocates pages for @chunk

 * @chunk: target chunk

 * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()

 * @populated: populated bitmap

 * @page_start: page index of the first page to be allocated

 * @page_end: page index of the last page to be allocated + 1

 *
@@ -104,8 +79,7 @@ static void pcpu_free_pages(struct pcpu_chunk *chunk, 
 * content of @pages and will pass it verbatim to pcpu_map_pages().

 */

static int pcpu_alloc_pages(struct pcpu_chunk *chunk,

			    struct page **pages, unsigned long *populated,

			    int page_start, int page_end)

			    struct page **pages, int page_start, int page_end)

{

	const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;

	unsigned int cpu, tcpu;
@@ -164,7 +138,6 @@ static void __pcpu_unmap_pages(unsigned long addr, int nr_pages) 
 * pcpu_unmap_pages - unmap pages out of a pcpu_chunk

 * @chunk: chunk of interest

 * @pages: pages array which can be used to pass information to free

 * @populated: populated bitmap

 * @page_start: page index of the first page to unmap

 * @page_end: page index of the last page to unmap + 1

 *
@@ -175,8 +148,7 @@ static void __pcpu_unmap_pages(unsigned long addr, int nr_pages) 
 * proper pre/post flush functions.

 */

static void pcpu_unmap_pages(struct pcpu_chunk *chunk,

			     struct page **pages, unsigned long *populated,

			     int page_start, int page_end)

			     struct page **pages, int page_start, int page_end)

{

	unsigned int cpu;

	int i;
@@ -192,8 +164,6 @@ static void pcpu_unmap_pages(struct pcpu_chunk *chunk, 
		__pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),

				   page_end - page_start);

	}



	bitmap_clear(populated, page_start, page_end - page_start);

}



/**
@@ -228,7 +198,6 @@ static int __pcpu_map_pages(unsigned long addr, struct page **pages, 
 * pcpu_map_pages - map pages into a pcpu_chunk

 * @chunk: chunk of interest

 * @pages: pages array containing pages to be mapped

 * @populated: populated bitmap

 * @page_start: page index of the first page to map

 * @page_end: page index of the last page to map + 1

 *
@@ -236,13 +205,11 @@ static int __pcpu_map_pages(unsigned long addr, struct page **pages, 
 * caller is responsible for calling pcpu_post_map_flush() after all

 * mappings are complete.

 *

 * This function is responsible for setting corresponding bits in

 * @chunk->populated bitmap and whatever is necessary for reverse

 * lookup (addr -> chunk).

 * This function is responsible for setting up whatever is necessary for

 * reverse lookup (addr -> chunk).

 */

static int pcpu_map_pages(struct pcpu_chunk *chunk,

			  struct page **pages, unsigned long *populated,

			  int page_start, int page_end)

			  struct page **pages, int page_start, int page_end)

{

	unsigned int cpu, tcpu;

	int i, err;
@@ -253,18 +220,12 @@ static int pcpu_map_pages(struct pcpu_chunk *chunk, 
				       page_end - page_start);

		if (err < 0)

			goto err;

	}



	/* mapping successful, link chunk and mark populated */

	for (i = page_start; i < page_end; i++) {

		for_each_possible_cpu(cpu)

		for (i = page_start; i < page_end; i++)

			pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],

					    chunk);

		__set_bit(i, populated);

	}



	return 0;



err:

	for_each_possible_cpu(tcpu) {

		if (tcpu == cpu)
@@ -314,7 +275,6 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) 
	int page_end = PFN_UP(off + size);

	int free_end = page_start, unmap_end = page_start;

	struct page **pages;

	unsigned long *populated;

	unsigned int cpu;

	int rs, re, rc;
@@ -327,28 +287,27 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) 
	/* need to allocate and map pages, this chunk can't be immutable */

	WARN_ON(chunk->immutable);



	pages = pcpu_get_pages_and_bitmap(chunk, &populated, true);

	pages = pcpu_get_pages(chunk, true);

	if (!pages)

		return -ENOMEM;



	/* alloc and map */

	pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {

		rc = pcpu_alloc_pages(chunk, pages, populated, rs, re);

		rc = pcpu_alloc_pages(chunk, pages, rs, re);

		if (rc)

			goto err_free;

		free_end = re;

	}



	pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {

		rc = pcpu_map_pages(chunk, pages, populated, rs, re);

		rc = pcpu_map_pages(chunk, pages, rs, re);

		if (rc)

			goto err_unmap;

		unmap_end = re;

	}

	pcpu_post_map_flush(chunk, page_start, page_end);



	/* commit new bitmap */

	bitmap_copy(chunk->populated, populated, pcpu_unit_pages);

	bitmap_set(chunk->populated, page_start, page_end - page_start);

clear:

	for_each_possible_cpu(cpu)

		memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
@@ -357,11 +316,11 @@ static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size) 
err_unmap:

	pcpu_pre_unmap_flush(chunk, page_start, unmap_end);

	pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)

		pcpu_unmap_pages(chunk, pages, populated, rs, re);

		pcpu_unmap_pages(chunk, pages, rs, re);

	pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);

err_free:

	pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)

		pcpu_free_pages(chunk, pages, populated, rs, re);

		pcpu_free_pages(chunk, pages, rs, re);

	return rc;

}
@@ -383,7 +342,6 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size) 
	int page_start = PFN_DOWN(off);

	int page_end = PFN_UP(off + size);

	struct page **pages;

	unsigned long *populated;

	int rs, re;



	/* quick path, check whether it's empty already */
@@ -400,22 +358,21 @@ static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size) 
	 * successful population attempt so the temp pages array must

	 * be available now.

	 */

	pages = pcpu_get_pages_and_bitmap(chunk, &populated, false);

	pages = pcpu_get_pages(chunk, false);

	BUG_ON(!pages);



	/* unmap and free */

	pcpu_pre_unmap_flush(chunk, page_start, page_end);



	pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)

		pcpu_unmap_pages(chunk, pages, populated, rs, re);

		pcpu_unmap_pages(chunk, pages, rs, re);



	/* no need to flush tlb, vmalloc will handle it lazily */



	pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)

		pcpu_free_pages(chunk, pages, populated, rs, re);

		pcpu_free_pages(chunk, pages, rs, re);



	/* commit new bitmap */

	bitmap_copy(chunk->populated, populated, pcpu_unit_pages);

	bitmap_clear(chunk->populated, page_start, page_end - page_start);

}



static struct pcpu_chunk *pcpu_create_chunk(void)