| From e048cb32f69038aa1c8f11e5c1b331be4181659d Mon Sep 17 00:00:00 2001 |
| From: Doug Berger <opendmb@gmail.com> |
| Date: Mon, 10 Jul 2017 15:49:44 -0700 |
| Subject: cma: fix calculation of aligned offset |
| |
| From: Doug Berger <opendmb@gmail.com> |
| |
| commit e048cb32f69038aa1c8f11e5c1b331be4181659d upstream. |
| |
| The align_offset parameter is used by bitmap_find_next_zero_area_off() |
| to represent the offset of map's base from the previous alignment |
| boundary; the function ensures that the returned index, plus the |
| align_offset, honors the specified align_mask. |
| |
| The logic introduced by commit b5be83e308f7 ("mm: cma: align to physical |
| address, not CMA region position") has the cma driver calculate the |
| offset to the *next* alignment boundary. In most cases, the base |
| alignment is greater than that specified when making allocations, |
| resulting in a zero offset whether we align up or down. In the example |
| given with the commit, the base alignment (8MB) was half the requested |
| alignment (16MB) so the math also happened to work since the offset is |
| 8MB in both directions. However, when requesting allocations with an |
| alignment greater than twice that of the base, the returned index would |
| not be correctly aligned. |
| |
| Also, the align_order arguments of cma_bitmap_aligned_mask() and |
| cma_bitmap_aligned_offset() should not be negative so the argument type |
| was made unsigned. |
| |
| Fixes: b5be83e308f7 ("mm: cma: align to physical address, not CMA region position") |
| Link: http://lkml.kernel.org/r/20170628170742.2895-1-opendmb@gmail.com |
| Signed-off-by: Angus Clark <angus@angusclark.org> |
| Signed-off-by: Doug Berger <opendmb@gmail.com> |
| Acked-by: Gregory Fong <gregory.0xf0@gmail.com> |
| Cc: Doug Berger <opendmb@gmail.com> |
| Cc: Angus Clark <angus@angusclark.org> |
| Cc: Laura Abbott <labbott@redhat.com> |
| Cc: Vlastimil Babka <vbabka@suse.cz> |
| Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Cc: Lucas Stach <l.stach@pengutronix.de> |
| Cc: Catalin Marinas <catalin.marinas@arm.com> |
| Cc: Shiraz Hashim <shashim@codeaurora.org> |
| Cc: Jaewon Kim <jaewon31.kim@samsung.com> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| mm/cma.c | 15 ++++++--------- |
| 1 file changed, 6 insertions(+), 9 deletions(-) |
| |
| --- a/mm/cma.c |
| +++ b/mm/cma.c |
| @@ -58,7 +58,7 @@ unsigned long cma_get_size(const struct |
| } |
| |
| static unsigned long cma_bitmap_aligned_mask(const struct cma *cma, |
| - int align_order) |
| + unsigned int align_order) |
| { |
| if (align_order <= cma->order_per_bit) |
| return 0; |
| @@ -66,17 +66,14 @@ static unsigned long cma_bitmap_aligned_ |
| } |
| |
| /* |
| - * Find a PFN aligned to the specified order and return an offset represented in |
| - * order_per_bits. |
| + * Find the offset of the base PFN from the specified align_order. |
| + * The value returned is represented in order_per_bits. |
| */ |
| static unsigned long cma_bitmap_aligned_offset(const struct cma *cma, |
| - int align_order) |
| + unsigned int align_order) |
| { |
| - if (align_order <= cma->order_per_bit) |
| - return 0; |
| - |
| - return (ALIGN(cma->base_pfn, (1UL << align_order)) |
| - - cma->base_pfn) >> cma->order_per_bit; |
| + return (cma->base_pfn & ((1UL << align_order) - 1)) |
| + >> cma->order_per_bit; |
| } |
| |
| static unsigned long cma_bitmap_maxno(struct cma *cma) |
