[PATCH 03/15] percpu: remove the usage of separate populated bitmap in percpu-vm
From: Tejun Heo
Date: Fri Aug 22 2014 - 12:53:45 EST
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 <tj@xxxxxxxxxx>
---
mm/percpu-vm.c | 93 ++++++++++++++++------------------------------------------
1 file changed, 25 insertions(+), 68 deletions(-)
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index 5110816..47b47bf 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -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)
- 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;
}
@@ -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 @@ clear:
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)
--
1.9.3
--
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