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linux/kernel/dma
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Zhenhua Huang f875db4f20 Revert "dma-contiguous: check for memory region overlap" 
This reverts commit 3fa6456ebe.

The Commit broke the CMA region creation through DT on arm64,
as showed below logs with "memblock=debug":
[    0.000000] memblock_phys_alloc_range: 41943040 bytes align=0x200000
from=0x0000000000000000 max_addr=0x00000000ffffffff
early_init_dt_alloc_reserved_memory_arch+0x34/0xa0
[    0.000000] memblock_reserve: [0x00000000fd600000-0x00000000ffdfffff]
memblock_alloc_range_nid+0xc0/0x19c
[    0.000000] Reserved memory: overlap with other memblock reserved region

>From call flow, region we defined in DT was always reserved before entering
into rmem_cma_setup. Also, rmem_cma_setup has one routine cma_init_reserved_mem
to ensure the region was reserved. Checking the region not reserved here seems
not correct.

early_init_fdt_scan_reserved_mem:
    fdt_scan_reserved_mem
        __reserved_mem_reserve_reg
		early_init_dt_reserve_memory
			memblock_reserve(using “reg” prop case)
        fdt_init_reserved_mem
		__reserved_mem_alloc_size
			*early_init_dt_alloc_reserved_memory_arch*
				memblock_reserve(dynamic alloc case)
        __reserved_mem_init_node
		rmem_cma_setup(region overlap check here should always fail)

Example DT can be used to reproduce issue:

    dump_mem: mem_dump_region {
            compatible = "shared-dma-pool";
            alloc-ranges = <0x0 0x00000000 0x0 0xffffffff>;
            reusable;
            size = <0 0x2800000>;
    };

Signed-off-by: Zhenhua Huang <quic_zhenhuah@quicinc.com>
2023-09-08 05:58:32 -03:00
..
coherent.c dma-mapping: Add dma_release_coherent_memory to DMA API 2022-06-24 09:30:54 -06:00
contiguous.c Revert "dma-contiguous: check for memory region overlap" 2023-09-08 05:58:32 -03:00
debug.c dma-debug: don't call __dma_entry_alloc_check_leak() under free_entries_lock 2023-08-30 11:29:08 +02:00
debug.h dma-debug: teach add_dma_entry() about DMA_ATTR_SKIP_CPU_SYNC 2021-10-18 12:46:45 +02:00
direct.c swiotlb: if swiotlb is full, fall back to a transient memory pool 2023-08-01 18:02:20 +02:00
direct.h dma-mapping: force bouncing if the kmalloc() size is not cache-line-aligned 2023-06-19 16:19:23 -07:00
dummy.c
Kconfig dma-contiguous: fix the Kconfig entry for CONFIG_DMA_NUMA_CMA 2023-08-30 13:52:53 +02:00
Makefile dma-mapping: remove CONFIG_DMA_REMAP 2022-03-03 14:00:57 +03:00
map_benchmark.c dma-mapping: benchmark: remove MODULE_LICENSE in non-modules 2023-04-13 13:13:51 -07:00
mapping.c dma-mapping: move arch_dma_set_mask() declaration to header 2023-07-31 17:54:28 +02:00
ops_helpers.c
pool.c dma-pool: remove a __maybe_unused label in atomic_pool_expand 2023-08-31 14:12:37 +02:00
remap.c dma-remap: use kvmalloc_array/kvfree for larger dma memory remap 2023-06-07 15:06:28 +02:00
swiotlb.c swiotlb: optimize get_max_slots() 2023-08-08 10:29:21 -07:00