mm: cma: align to physical address, not CMA region position (b5be83e3) · Commits · 戴 / test

The alignment in cma_alloc() was done w.r.t. the bitmap. This is a problem when, for example: - a device requires 16M (order 12) alignment - the CMA region is not 16 M aligned In such a case, can result with the CMA region starting at, say, 0x2f800000 but any allocation you make from there will be aligned from there. Requesting an allocation of 32 M with 16 M alignment will result in an allocation from 0x2f800000 to 0x31800000, which doesn't work very well if your strange device requires 16M alignment. Change to use bitmap_find_next_zero_area_off() to account for the difference in alignment at reserve-time and alloc-time. Signed-off-by:

Gregory Fong <gregory.0xf0@gmail.com> Acked-by:

Michal Nazarewicz <mina86@mina86.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Cc: Laura Abbott <lauraa@codeaurora.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

mm/cma.c

+16 −3

Original line number	Diff line number	Diff line
		@@ -63,6 +63,17 @@ static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order)
		return (1UL << (align_order - cma->order_per_bit)) - 1;
		}

		static unsigned long cma_bitmap_aligned_offset(struct cma *cma, int align_order)
		{
		unsigned int alignment;

		if (align_order <= cma->order_per_bit)
		return 0;
		alignment = 1UL << (align_order - cma->order_per_bit);
		return ALIGN(cma->base_pfn, alignment) -
		(cma->base_pfn >> cma->order_per_bit);
		}

		static unsigned long cma_bitmap_maxno(struct cma *cma)
		{
		return cma->count >> cma->order_per_bit;
		@@ -340,7 +351,7 @@ err:
		*/
		struct page cma_alloc(struct cma cma, int count, unsigned int align)
		{
		unsigned long mask, pfn, start = 0;
		unsigned long mask, offset, pfn, start = 0;
		unsigned long bitmap_maxno, bitmap_no, bitmap_count;
		struct page *page = NULL;
		int ret;
		@@ -355,13 +366,15 @@ struct page cma_alloc(struct cma cma, int count, unsigned int align)
		return NULL;

		mask = cma_bitmap_aligned_mask(cma, align);
		offset = cma_bitmap_aligned_offset(cma, align);
		bitmap_maxno = cma_bitmap_maxno(cma);
		bitmap_count = cma_bitmap_pages_to_bits(cma, count);

		for (;;) {
		mutex_lock(&cma->lock);
		bitmap_no = bitmap_find_next_zero_area(cma->bitmap,
		bitmap_maxno, start, bitmap_count, mask);
		bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap,
		bitmap_maxno, start, bitmap_count, mask,
		offset);
		if (bitmap_no >= bitmap_maxno) {
		mutex_unlock(&cma->lock);
		break;

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