From: Russell King - ARM Linux [mailto:linux at arm.linux.org.uk]
Sent: Thursday, June 28, 2012 4:18 AM
On Fri, Jun 08, 2012 at 10:58:50PM +0900, Kim, Jong-Sung wrote:

quoted

May I suggest another simple approach? The first continuous couples of
sections are always safely section-mapped inside alloc_init_section

funtion.

quoted

So, by limiting memblock_alloc to the end of the first continuous
couples of sections at the start of map_lowmem, map_lowmem can safely
memblock_alloc & memset even if we have one or more section-unaligned
memory regions. The limit can be extended back to arm_lowmem_limit after

the map_lowmem is done.

No.  What if the first block of memory is not large enough to handle all

the

allocations?

Thank you for your comment, Russell. I sent a modified patch not to limit to
the first memory memblock_region as a reply to Dave's message.

I think the real problem is folk trying to reserve small amounts.  I have
said all reservations must be aligned to 1MB.

Ok, now I know your thought about arm_memblock_steal(). Then, how about
adding a simple aligning to prevent the possible problem just like me:

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index f54d592..d0daf0d 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c

@@ -324,6 +324,8 @@ phys_addr_t __init arm_memblock_steal(phys_addr_t size,

phys
 
        BUG_ON(!arm_memblock_steal_permitted);
 
+       size = ALIGN(size, SECTION_SIZE);
+
        phys = memblock_alloc(size, align);
        memblock_free(phys, size);
        memblock_remove(phys, size);

or, leaving a few comments about the restriction kindly..?