Automatically allocated regions should not cross low/high memory boundary,
because such regions cannot be later correctly initialized due to spanning
across two memory zones. This patch adds a check for this case and a simple
code for moving region to low memory if automatically selected address might
not fit completely into high memory.
Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
mm/cma.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/mm/cma.c b/mm/cma.c
index c17751c0dcaf..4acc6aa4a086 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -32,6 +32,7 @@
#include <linux/slab.h>
#include <linux/log2.h>
#include <linux/cma.h>
+#include <linux/highmem.h>
struct cma {
unsigned long base_pfn;
@@ -163,6 +164,8 @@ int __init cma_declare_contiguous(phys_addr_t base,
bool fixed, struct cma **res_cma)
{
struct cma *cma;
+ phys_addr_t memblock_end = memblock_end_of_DRAM();
+ phys_addr_t highmem_start = __pa(high_memory);
int ret = 0;
pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n",
@@ -196,6 +199,24 @@ int __init cma_declare_contiguous(phys_addr_t base,
if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit))
return -EINVAL;
+ /*
+ * adjust limit to avoid crossing low/high memory boundary for
+ * automatically allocated regions
+ */
+ if (((limit == 0 || limit > memblock_end) &&
+ (memblock_end - size < highmem_start &&
+ memblock_end > highmem_start)) ||
+ (!fixed && limit > highmem_start && limit - size < highmem_start)) {
+ limit = highmem_start;
+ }
+
+ if (fixed && base < highmem_start && base+size > highmem_start) {
+ ret = -EINVAL;
+ pr_err("Region at %08lx defined on low/high memory boundary (%08lx)\n",
+ (unsigned long)base, (unsigned long)highmem_start);
+ goto err;
+ }
+
/* Reserve memory */
if (base && fixed) {
if (memblock_is_region_reserved(base, size) ||
--
1.9.2
--
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