Skip to content

Commit

Permalink
percpu: remove the usage of separate populated bitmap in percpu-vm
Browse files Browse the repository at this point in the history 
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: Tejun Heo <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
  • Loading branch information
@htejun
htejun committed Sep 2, 2014
1 parent 3189edd commit fbbb7f4
Showing 1 changed file with 25 additions and 68 deletions.
93 changes: 25 additions & 68 deletions mm/percpu-vm.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -20,63 +20,39 @@ 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)
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;
if (!pages && may_alloc)
pages = pcpu_mem_zalloc(pages_size);
return pages;
}

/**
* 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
*
* Free pages [@page_start and @page_end) in @pages for all units.
* 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;
Expand All @@ -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
*
Expand All @@ -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;
Expand Down Expand Up @@ -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
*
Expand All @@ -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;
Expand All @@ -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);
}

/**
Expand Down Expand Up @@ -228,21 +198,18 @@ 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
*
* For each cpu, map pages [@page_start,@page_end) into @chunk. The
* 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;
Expand All @@ -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)
Expand Down Expand Up @@ -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;

Expand All @@ -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);
Expand All @@ -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;
}

Expand All @@ -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 */
Expand All @@ -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)
Expand Down

0 comments on commit fbbb7f4

Please sign in to comment.