Add memblock_cap_memory_range() which will remove all the memblock regions except the range specified in the arguments. This function, like memblock_mem_limit_remove_map(), will not remove memblocks with MEMMAP_NOMAP attribute as they may be mapped and accessed later as "device memory." See the commit a571d4eb55d8 ("mm/memblock.c: add new infrastructure to address the mem limit issue"). This function is used, in a succeeding patch in the series of arm64 kdump suuport, to limit the range of usable memory, System RAM, on crash dump kernel. (Please note that "mem=" parameter is of little use for this purpose.) Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx> Cc: linux-mm@xxxxxxxxx Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/memblock.h | 1 + mm/memblock.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/include/linux/memblock.h b/include/linux/memblock.h index 5b759c9..0e770af 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -334,6 +334,7 @@ phys_addr_t memblock_start_of_DRAM(void); phys_addr_t memblock_end_of_DRAM(void); void memblock_enforce_memory_limit(phys_addr_t memory_limit); void memblock_mem_limit_remove_map(phys_addr_t limit); +void memblock_cap_memory_range(phys_addr_t base, phys_addr_t size); bool memblock_is_memory(phys_addr_t addr); int memblock_is_map_memory(phys_addr_t addr); int memblock_is_region_memory(phys_addr_t base, phys_addr_t size); diff --git a/mm/memblock.c b/mm/memblock.c index 7608bc3..eb53876 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1544,6 +1544,34 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit) (phys_addr_t)ULLONG_MAX); } +void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size) +{ + int start_rgn, end_rgn; + int i, ret; + + if (!size) + return; + + ret = memblock_isolate_range(&memblock.memory, base, size, + &start_rgn, &end_rgn); + if (ret) + return; + + /* remove all the MAP regions */ + for (i = memblock.memory.cnt - 1; i >= end_rgn; i--) + if (!memblock_is_nomap(&memblock.memory.regions[i])) + memblock_remove_region(&memblock.memory, i); + + for (i = start_rgn - 1; i >= 0; i--) + if (!memblock_is_nomap(&memblock.memory.regions[i])) + memblock_remove_region(&memblock.memory, i); + + /* truncate the reserved regions */ + memblock_remove_range(&memblock.reserved, 0, base); + memblock_remove_range(&memblock.reserved, + base + size, (phys_addr_t)ULLONG_MAX); +} + static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr) { unsigned int left = 0, right = type->cnt; -- 2.10.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>