Commit 6b9d7c8e authored by Dennis Zhou (Facebook)'s avatar Dennis Zhou (Facebook) Committed by Tejun Heo
Browse files

percpu: end chunk area maps page aligned for the populated bitmap 



The area map allocator manages the first chunk area by hiding all but
the region it is responsible for serving in the area map. To align this
with the populated page bitmap, end_offset is introduced to keep track
of the delta to end page aligned. The area map is appended with the
page aligned end when necessary to be in line with how the bitmap
allocator requires the ending to be aligned with the LCM of PAGE_SIZE
and the size of each bitmap block. percpu_stats is updated to ignore
this region when present.

Signed-off-by: default avatarDennis Zhou <dennisszhou@gmail.com>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 10edf5b0

mm/percpu-internal.h

+3 −0
Original line number Diff line number Diff line
@@ -26,6 +26,9 @@ struct pcpu_chunk { 
	int			start_offset;	/* the overlap with the previous

						   region to have a page aligned

						   base_addr */

	int			end_offset;	/* additional area required to

						   have the region end page

						   aligned */

	int			nr_populated;	/* # of populated pages */

	unsigned long		populated[];	/* populated bitmap */

};

mm/percpu-stats.c

+3 −2
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ static int find_max_map_used(void) 
static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk,

			    int *buffer)

{

	int i, s_index, last_alloc, alloc_sign, as_len;

	int i, s_index, e_index, last_alloc, alloc_sign, as_len;

	int *alloc_sizes, *p;

	/* statistics */

	int sum_frag = 0, max_frag = 0;
@@ -59,10 +59,11 @@ static void chunk_map_stats(struct seq_file *m, struct pcpu_chunk *chunk, 


	alloc_sizes = buffer;

	s_index = (chunk->start_offset) ? 1 : 0;

	e_index = chunk->map_used - ((chunk->end_offset) ? 1 : 0);



	/* find last allocation */

	last_alloc = -1;

	for (i = chunk->map_used - 1; i >= s_index; i--) {

	for (i = e_index - 1; i >= s_index; i--) {

		if (chunk->map[i] & 1) {

			last_alloc = i;

			break;

mm/percpu.c

+9 −0
Original line number Diff line number Diff line
@@ -715,12 +715,16 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(void *base_addr, 
							 int init_map_size)

{

	struct pcpu_chunk *chunk;

	int region_size;



	region_size = PFN_ALIGN(start_offset + map_size);



	chunk = memblock_virt_alloc(pcpu_chunk_struct_size, 0);

	INIT_LIST_HEAD(&chunk->list);

	INIT_LIST_HEAD(&chunk->map_extend_list);

	chunk->base_addr = base_addr;

	chunk->start_offset = start_offset;

	chunk->end_offset = region_size - chunk->start_offset - map_size;

	chunk->map = map;

	chunk->map_alloc = init_map_size;
@@ -735,6 +739,11 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(void *base_addr, 
	chunk->map[2] = (chunk->start_offset + chunk->free_size) | 1;

	chunk->map_used = 2;



	if (chunk->end_offset) {

		/* hide the end of the bitmap */

		chunk->map[++chunk->map_used] = region_size | 1;

	}



	return chunk;

}

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