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Subject[PATCH 22/49] memblock: Add arch function to control coalescing of memblock memory regions
Date
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Some archs such as ARM want to avoid coalescing accross things such
as the lowmem/highmem boundary or similar. This provides the option
to control it via an arch callback for which a weak default is provided
which always allows coalescing.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
include/linux/memblock.h | 2 ++
mm/memblock.c | 19 ++++++++++++++++++-
2 files changed, 20 insertions(+), 1 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index b839053..15da7d9 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -70,6 +70,8 @@ extern void memblock_dump_all(void);

/* Provided by the architecture */
extern phys_addr_t memblock_nid_range(phys_addr_t start, phys_addr_t end, int *nid);
+extern int memblock_memory_can_coalesce(phys_addr_t addr1, phys_addr_t size1,
+ phys_addr_t addr2, phys_addr_t size2);

/**
* memblock_set_current_limit - Set the current allocation limit to allow
diff --git a/mm/memblock.c b/mm/memblock.c
index 8197f37..f793d9f 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -241,6 +241,12 @@ static int memblock_double_array(struct memblock_type *type)
return 0;
}

+extern int __weak memblock_memory_can_coalesce(phys_addr_t addr1, phys_addr_t size1,
+ phys_addr_t addr2, phys_addr_t size2)
+{
+ return 1;
+}
+
static long memblock_add_region(struct memblock_type *type, phys_addr_t base, phys_addr_t size)
{
unsigned long coalesced = 0;
@@ -262,6 +268,10 @@ static long memblock_add_region(struct memblock_type *type, phys_addr_t base, ph
return 0;

adjacent = memblock_addrs_adjacent(base, size, rgnbase, rgnsize);
+ /* Check if arch allows coalescing */
+ if (adjacent != 0 && type == &memblock.memory &&
+ !memblock_memory_can_coalesce(base, size, rgnbase, rgnsize))
+ break;
if (adjacent > 0) {
type->regions[i].base -= size;
type->regions[i].size += size;
@@ -274,7 +284,14 @@ static long memblock_add_region(struct memblock_type *type, phys_addr_t base, ph
}
}

- if ((i < type->cnt - 1) && memblock_regions_adjacent(type, i, i+1)) {
+ /* If we plugged a hole, we may want to also coalesce with the
+ * next region
+ */
+ if ((i < type->cnt - 1) && memblock_regions_adjacent(type, i, i+1) &&
+ ((type != &memblock.memory || memblock_memory_can_coalesce(type->regions[i].base,
+ type->regions[i].size,
+ type->regions[i+1].base,
+ type->regions[i+1].size)))) {
memblock_coalesce_regions(type, i, i+1);
coalesced++;
}
--
1.6.4.2


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