[PATCH v27 1/9] memblock: add memblock_cap_memory_range()
From: AKASHI Takahiro <hidden>
Date: 2016-11-14 05:46:41
Also in:
kexec, linux-mm
Subsystem:
memblock and memory management initialization, memory management, the rest · Maintainers:
Mike Rapoport, Andrew Morton, Linus Torvalds
On Fri, Nov 11, 2016 at 11:19:04AM +0800, Dennis Chen wrote:
On Fri, Nov 11, 2016 at 11:50:50AM +0900, AKASHI Takahiro wrote:quoted
Will, (+ Cc: Dennis) On Thu, Nov 10, 2016 at 05:27:20PM +0000, Will Deacon wrote:quoted
On Wed, Nov 02, 2016 at 01:51:53PM +0900, AKASHI Takahiro wrote:quoted
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 <redacted> Cc: linux-mm at kvack.org Cc: Andrew Morton <akpm@linux-foundation.org> --- 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); +}This duplicates a bunch of the logic in memblock_mem_limit_remove_map. Can you not implement that in terms of your new, more general, function? e.g. by passing base == 0, and size == limit?Obviously it's possible. I actually talked to Dennis before about merging them, but he was against my idea.Oops! I thought we have reached agreement in the thread:http://lists.infradead.org/pipermail/linux-arm-kernel/2016-July/442817.html So feel free to do that as Will'll do
OK, but I found that the two functions have a bit different semantics in clipping memory range, in particular, when the range [base,base+size) goes across several regions with a gap. (This does not happen in my arm64 kdump, though.) That is, 'limit' in memblock_mem_limit_remove_map() means total size of available memory, while 'size' in memblock_cap_memory_range() indicates the size of _continuous_ memory range. So I added an extra argument, exact, to a common function to specify distinct behaviors. Confusing? Please see the patch below. If nobody objects to this merge, I will submit a whole patchset of kdump again. Thanks, -Takahiro AKASHI ===8<=== include/linux/memblock.h | 1 + mm/memblock.c | 91 +++++++++++++++++++++++++++++++++++------------- 2 files changed, 68 insertions(+), 24 deletions(-)
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..5f849a9 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c@@ -1473,9 +1473,10 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void) return (memblock.memory.regions[idx].base + memblock.memory.regions[idx].size); } -static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit) +static phys_addr_t __init_memblock __find_max_addr(phys_addr_t min, + phys_addr_t limit) { - phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX; + phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX, base, size; struct memblock_region *r; /*
@@ -1484,11 +1485,22 @@ static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit) * of those regions, max_addr will keep original value ULLONG_MAX */ for_each_memblock(memory, r) { - if (limit <= r->size) { - max_addr = r->base + limit; + if (min >= r->base + r->size) + continue; + + if (r->base <= min) { + base = min; + size = r->base + r->size - min; + } else { + base = r->base; + size = r->size; + } + + if (limit <= size) { + max_addr = base + limit; break; } - limit -= r->size; + limit -= size; } return max_addr;
@@ -1501,7 +1513,7 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) if (!limit) return; - max_addr = __find_max_addr(limit); + max_addr = __find_max_addr(0, limit); /* @limit exceeds the total size of the memory, do nothing */ if (max_addr == (phys_addr_t)ULLONG_MAX)
@@ -1514,34 +1526,65 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit) (phys_addr_t)ULLONG_MAX); } -void __init memblock_mem_limit_remove_map(phys_addr_t limit) +/* + * __memblock_cap_memory_range - cap memblock regions + * @base: lowest address to clip + * @size: size of memory range + * @exact: true or false + * + * If @exact is true, the exact range [@base, @base+ at size) of memory with + * kernel direct mapping is clipped from memblock.memory. Otherwise, total + * of @size of memory is clipped starting from @base. + */ +static void __init __memblock_cap_memory_range(phys_addr_t base, + phys_addr_t size, bool exact) { - struct memblock_type *type = &memblock.memory; - phys_addr_t max_addr; - int i, ret, start_rgn, end_rgn; + int start_rgn, end_rgn; + int i, ret; - if (!limit) + if (!size) return; - max_addr = __find_max_addr(limit); + if (!exact) { + phys_addr_t max_addr; - /* @limit exceeds the total size of the memory, do nothing */ - if (max_addr == (phys_addr_t)ULLONG_MAX) - return; + max_addr = __find_max_addr(base, size); + /* @size exceeds the total size of the memory, do nothing */ + if (max_addr == (phys_addr_t)ULLONG_MAX) + return; + + /* recalc the size to clip the exact range [@base, max_addr) */ + size = max_addr - base; + } - ret = memblock_isolate_range(type, max_addr, (phys_addr_t)ULLONG_MAX, - &start_rgn, &end_rgn); + ret = memblock_isolate_range(&memblock.memory, base, size, + &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); - } + /* remove all the other 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, max_addr, - (phys_addr_t)ULLONG_MAX); + 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) +{ + __memblock_cap_memory_range(0, limit, false); +} + +void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size) +{ + __memblock_cap_memory_range(base, size, true); } static int __init_memblock memblock_search(struct memblock_type *type, phys_addr_t addr)
--
2.10.0
===>8===
> >
> > Thanks,
> > -Takahiro AKASHI
> >
> > > Will