Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Levi Yun <> | Subject | [PATCH] mm/cma: Fix potential memory loss on cma_declare_contiguous_nid | Date | Wed, 18 Jan 2023 17:05:23 +0900 |
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Suppose, memblock_alloc_ranged_nid with highmem_start is success when cma_declare_contiguous_nid is called with !fixed in the system 32-bit system with PHYS_ADDR_T_64BIT enabled with memblock.bottom_up == false.
But, Next trial to memblock_alloc_range_nid to allocate in [SIZE_4G, limits) nullifies former success allocated addr and it retries to memblock_alloc_ragne_nid again.
In this situation, first success address area is lost.
By changing order of allocation (SIZE_4G, high_memory and base) and checking whether allocated prevents potential memory lost.
Signed-off-by: Levi Yun <ppbuk5246@gmail.com> --- mm/cma.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/mm/cma.c b/mm/cma.c index 4a978e09547a..49d9b08d9a47 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -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); -- 2.35.1
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