From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Subject: ARM: CMA: avoid double mapping to the CMA area if CONFIG_HIGHMEM=y CMA area is now managed by the separate zone, ZONE_MOVABLE, to fix many MM related problems. In this implementation, if CONFIG_HIGHMEM = y, then ZONE_MOVABLE is considered as HIGHMEM and the memory of the CMA area is also considered as HIGHMEM. That means that they are considered as the page without direct mapping. However, CMA area could be in a lowmem and the memory could have direct mapping. In ARM, when establishing a new mapping for DMA, direct mapping should be cleared since two mapping with different cache policy could cause unknown problem. With this patch, PageHighmem() for the CMA memory located in lowmem returns true so that the function for DMA mapping cannot notice whether it needs to clear direct mapping or not, correctly. To handle this situation, this patch always clears direct mapping for such CMA memory. Link: http://lkml.kernel.org/r/1512114786-5085-4-git-send-email-iamjoonsoo.kim@xxxxxxx Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Tested-by: Tony Lindgren <tony@xxxxxxxxxxx> Cc: "Aneesh Kumar K . V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Laura Abbott <lauraa@xxxxxxxxxxxxxx> Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Michal Nazarewicz <mina86@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm/mm/dma-mapping.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff -puN arch/arm/mm/dma-mapping.c~arm-cma-avoid-double-mapping-to-the-cma-area-if-config_highmem-=-y arch/arm/mm/dma-mapping.c --- a/arch/arm/mm/dma-mapping.c~arm-cma-avoid-double-mapping-to-the-cma-area-if-config_highmem-=-y +++ a/arch/arm/mm/dma-mapping.c @@ -466,6 +466,12 @@ void __init dma_contiguous_early_fixup(p void __init dma_contiguous_remap(void) { int i; + + if (!dma_mmu_remap_num) + return; + + /* call flush_cache_all() since CMA area would be large enough */ + flush_cache_all(); for (i = 0; i < dma_mmu_remap_num; i++) { phys_addr_t start = dma_mmu_remap[i].base; phys_addr_t end = start + dma_mmu_remap[i].size; @@ -498,7 +504,15 @@ void __init dma_contiguous_remap(void) flush_tlb_kernel_range(__phys_to_virt(start), __phys_to_virt(end)); - iotable_init(&map, 1); + /* + * All the memory in CMA region will be on ZONE_MOVABLE. + * If that zone is considered as highmem, the memory in CMA + * region is also considered as highmem even if it's + * physical address belong to lowmem. In this case, + * re-mapping isn't required. + */ + if (!is_highmem_idx(ZONE_MOVABLE)) + iotable_init(&map, 1); } } _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
