Re: [PATCH] of: alloc anywhere from memblock if range not specified

From: Leonard Crestez
Date: Tue Jan 10 2017 - 11:16:55 EST


Hello,

I have some trouble with this patch.

It seems the intention is to allow CMA to be placed in highmem. If the CMA area is larger than highmem and no alloc-ranges is specified (just a size) it is possible to end up allocating a area that spans from multiple zones. This later breaks checks in cma_activate_area and makes most dma allocations fail.

Am I missing something or this a bug?

On Mon, Feb 22, 2016 at 3:45 PM, Vinayak Menon <vinmenon@xxxxxxxxxxxxxx> wrote:

early_init_dt_alloc_reserved_memory_arch passes end as 0 to
__memblock_alloc_base, when limits are not specified. But
__memblock_alloc_base takes end value of 0 as MEMBLOCK_ALLOC_ACCESSIBLE
and limits the end to memblock.current_limit. This results in regions
never being placed in HIGHMEM area, for e.g. CMA.
Let __memblock_alloc_base allocate from anywhere in memory if limits are
not specified.

Acked-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Vinayak Menon <vinmenon@xxxxxxxxxxxxxx>
---
drivers/of/of_reserved_mem.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 1a3556a..ed01c01 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -32,11 +32,13 @@ int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
phys_addr_t align, phys_addr_t start, phys_addr_t end, bool nomap,
phys_addr_t *res_base)
{
+ phys_addr_t base;
/*
* We use __memblock_alloc_base() because memblock_alloc_base()
* panic()s on allocation failure.
*/
- phys_addr_t base = __memblock_alloc_base(size, align, end);
+ end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
+ base = __memblock_alloc_base(size, align, end);
if (!base)
return -ENOMEM;

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member of the Code Aurora Forum, hosted by The Linux Foundation