Commit 148aa87e authored by Levi Yun's avatar Levi Yun Committed by Andrew Morton
Browse files

mm/cma: fix potential memory loss on cma_declare_contiguous_nid 

Suppose memblock_alloc_range_nid() with highmem_start succeeds when
cma_declare_contiguous_nid is called with !fixed on a 32-bit system with
PHYS_ADDR_T_64BIT enabled with memblock.bottom_up == false.

But the next trial to memblock_alloc_range_nid() to allocate in [SIZE_4G,
limits) nullifies former successfully allocated addr and it retries
memblock_alloc_ragne_nid().

In this situation, the first successfully allocated address area is lost.

Change the order of allocation (SIZE_4G, high_memory and base) and check
whether the allocated succeeded to prevent potential memory loss.

Link: https://lkml.kernel.org/r/20230118080523.44522-1-ppbuk5246@gmail.com


Signed-off-by: default avatarLevi Yun <ppbuk5246@gmail.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5649d113

mm/cma.c

+12 −12
Original line number Diff line number Diff line
@@ -321,18 +321,6 @@ int __init cma_declare_contiguous_nid(phys_addr_t base, 
	} else {

		phys_addr_t addr = 0;



		/*

		 * All pages in the reserved area must come from the same zone.

		 * If the requested region crosses the low/high memory boundary,

		 * try allocating from high memory first and fall back to low

		 * memory in case of failure.

		 */

		if (base < highmem_start && limit > highmem_start) {

			addr = memblock_alloc_range_nid(size, alignment,

					highmem_start, limit, nid, true);

			limit = highmem_start;

		}



		/*

		 * If there is enough memory, try a bottom-up allocation first.

		 * It will place the new cma area close to the start of the node
@@ -350,6 +338,18 @@ int __init cma_declare_contiguous_nid(phys_addr_t base, 
		}

#endif



		/*

		 * All pages in the reserved area must come from the same zone.

		 * If the requested region crosses the low/high memory boundary,

		 * try allocating from high memory first and fall back to low

		 * memory in case of failure.

		 */

		if (!addr && base < highmem_start && limit > highmem_start) {

			addr = memblock_alloc_range_nid(size, alignment,

					highmem_start, limit, nid, true);

			limit = highmem_start;

		}



		if (!addr) {

			addr = memblock_alloc_range_nid(size, alignment, base,

					limit, nid, true);