ARM: DMA coherent allocator: align remapped addresses

The DMA coherent remap area is used to provide an uncached mapping
of memory for coherency with DMA engines.  Currently, we look for
any free hole which our allocation will fit in with page alignment.

However, this can lead to fragmentation of the area, and allows small
allocations to cross L1 entry boundaries.  This is undesirable as we
want to move towards allocating sections of memory.

Align allocations according to the size, limiting the alignment between
the page and section sizes.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/arm/mm/vmregion.c b/arch/arm/mm/vmregion.c
index 19e09bdb1b8a..935993e1b1ef 100644
--- a/arch/arm/mm/vmregion.c
+++ b/arch/arm/mm/vmregion.c
@@ -35,7 +35,8 @@
  */
 
 struct arm_vmregion *
-arm_vmregion_alloc(struct arm_vmregion_head *head, size_t size, gfp_t gfp)
+arm_vmregion_alloc(struct arm_vmregion_head *head, size_t align,
+                   size_t size, gfp_t gfp)
 {
         unsigned long addr = head->vm_start, end = head->vm_end - size;
         unsigned long flags;
@@ -58,7 +59,7 @@ arm_vmregion_alloc(struct arm_vmregion_head *head, size_t size, gfp_t gfp)
                         goto nospc;
                 if ((addr + size) <= c->vm_start)
                         goto found;
-                addr = c->vm_end;
+                addr = ALIGN(c->vm_end, align);
                 if (addr > end)
                         goto nospc;
         }