The current memblock allocates memory from high address to low. And it has
a highest limit.
The next coming patches will improve memblock to be able to allocate memory
from low address to high. So we need a lowest limit.
Introduce current_limit_low to memblock. When users specify start address
as MEMBLOCK_ALLOC_ACCESSIBLE, memblock will use current_limit_low as the
low limit of allocation.
Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Reviewed-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
---
include/linux/memblock.h | 1 +
mm/memblock.c | 18 +++++++++++++++---
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index c28cd6b..40eb18e 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -35,6 +35,7 @@ struct memblock_type {
};
struct memblock {
+ phys_addr_t current_limit_low; /* lower boundary of accessable range */
phys_addr_t current_limit_high; /* upper boundary of accessable range */
struct memblock_type memory;
struct memblock_type reserved;
diff --git a/mm/memblock.c b/mm/memblock.c
index d351911..0dd5387 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -32,6 +32,7 @@ struct memblock memblock __initdata_memblock = {
.reserved.cnt = 1, /* empty dummy entry */
.reserved.max = INIT_MEMBLOCK_REGIONS,
+ .current_limit_low = 0,
.current_limit_high = MEMBLOCK_ALLOC_ANYWHERE,
};
@@ -84,7 +85,7 @@ static long __init_memblock memblock_overlaps_region(struct memblock_type *type,
/**
* memblock_find_in_range_node - find free area in given range and node
- * @start: start of candidate range
+ * @start: start of candidate range, can be %MEMBLOCK_ALLOC_ACCESSIBLE
* @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
* @size: size of free area to find
* @align: alignment of free area to find
@@ -92,6 +93,15 @@ static long __init_memblock memblock_overlaps_region(struct memblock_type *type,
*
* Find @size free area aligned to @align in the specified range and node.
*
+ * If @start is %MEMBLOCK_ALLOC_ACCESSIBLE, then set @start to
+ * memblock.current_limit_low which limit the lowest address memblock could
+ * access. %MEMBLOCK_ALLOC_ACCESSIBLE means nothing to @start.
+ *
+ * If @end is %MEMBLOCK_ALLOC_ACCESSIBLE, then set @start to
+ * memblock.current_limit_high which limit the highest address memblock could
+ * access. @end can also be %MEMBLOCK_ALLOC_ANYWHERE, which is the maximum
+ * physical address.
+ *
* RETURNS:
* Found address on success, %0 on failure.
*/
@@ -102,7 +112,9 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start,
phys_addr_t this_start, this_end, cand;
u64 i;
- /* pump up @end */
+ /* pump up @start and @end */
+ if (start == MEMBLOCK_ALLOC_ACCESSIBLE)
+ start = memblock.current_limit_low;
if (end == MEMBLOCK_ALLOC_ACCESSIBLE)
end = memblock.current_limit_high;
@@ -126,7 +138,7 @@ phys_addr_t __init_memblock memblock_find_in_range_node(phys_addr_t start,
/**
* memblock_find_in_range - find free area in given range
- * @start: start of candidate range
+ * @start: start of candidate range, can be %MEMBLOCK_ALLOC_ACCESSIBLE
* @end: end of candidate range, can be %MEMBLOCK_ALLOC_{ANYWHERE|ACCESSIBLE}
* @size: size of free area to find
* @align: alignment of free area to find
--
1.7.1
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