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memblock: add memblock_cap_memory_range() 

Add memblock_cap_memory_range() which will remove all the memblock regions
except the memory range specified in the arguments. In addition, rework is
done on memblock_mem_limit_remove_map() to re-implement it using
memblock_cap_memory_range().

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 a571d4eb55 ("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, or 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@linaro.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Dennis Chen <dennis.chen@arm.com>
Cc: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
AKASHI Takahiro 2017-04-03 11:23:55 +09:00 committed by Catalin Marinas
parent 4c546b8a34
commit c9ca9b4e21
2 changed files with 30 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/memblock.h
View File

@ -336,6 +336,7 @@ phys_addr_t memblock_mem_size(unsigned long limit_pfn);
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_cap_memory_range(phys_addr_t base, phys_addr_t size);
void memblock_mem_limit_remove_map(phys_addr_t limit);
bool memblock_is_memory(phys_addr_t addr);
int memblock_is_map_memory(phys_addr_t addr);

44
mm/memblock.c
View File

@ -1543,11 +1543,37 @@ void __init memblock_enforce_memory_limit(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);
}
void __init memblock_mem_limit_remove_map(phys_addr_t limit)
{
struct memblock_type *type = &memblock.memory;
phys_addr_t max_addr;
int i, ret, start_rgn, end_rgn;
if (!limit)
return;
@ -1558,19 +1584,7 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit)
if (max_addr == (phys_addr_t)ULLONG_MAX)
return;
ret = memblock_isolate_range(type, max_addr, (phys_addr_t)ULLONG_MAX,
&start_rgn, &end_rgn);
if (ret)
return;
/* remove all the MAP regions above the limit */
for (i = end_rgn - 1; i >= start_rgn; i--) {
if (!memblock_is_nomap(&type->regions[i]))
memblock_remove_region(type, i);
}
/* truncate the reserved regions */
memblock_remove_range(&memblock.reserved, max_addr,
(phys_addr_t)ULLONG_MAX);
memblock_cap_memory_range(0, max_addr);
}
static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)