There is no guarantee to CMA's placement, so allocating a zone specific
atomic pool from CMA might return memory from a completely different
memory zone. To get around this double check CMA's placement before
allocating from it.
Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp mask")
Reported-by: Jeremy Linton <[email protected]>
Signed-off-by: Nicolas Saenz Julienne <[email protected]>
---
This is a code intensive alternative to "dma-pool: Do not allocate pool
memory from CMA"[1].
[1] https://lkml.org/lkml/2020/7/8/1108
kernel/dma/pool.c | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 8cfa01243ed2..ccf3eeb77e00 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -3,6 +3,7 @@
* Copyright (C) 2012 ARM Ltd.
* Copyright (C) 2020 Google LLC
*/
+#include <linux/cma.h>
#include <linux/debugfs.h>
#include <linux/dma-direct.h>
#include <linux/dma-noncoherent.h>
@@ -56,6 +57,39 @@ static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
pool_size_kernel += size;
}
+static bool cma_in_zone(gfp_t gfp)
+{
+ u64 zone_dma_end, zone_dma32_end;
+ phys_addr_t base, end;
+ unsigned long size;
+ struct cma *cma;
+
+ cma = dev_get_cma_area(NULL);
+ if (!cma)
+ return false;
+
+ size = cma_get_size(cma);
+ if (!size)
+ return false;
+ base = cma_get_base(cma) - memblock_start_of_DRAM();
+ end = base + size - 1;
+
+ zone_dma_end = IS_ENABLED(CONFIG_ZONE_DMA) ? DMA_BIT_MASK(zone_dma_bits) : 0;
+ zone_dma32_end = IS_ENABLED(CONFIG_ZONE_DMA32) ? DMA_BIT_MASK(32) : 0;
+
+ /* CMA can't cross zone boundaries, see cma_activate_area() */
+ if (IS_ENABLED(CONFIG_ZONE_DMA) && gfp & GFP_DMA &&
+ end <= zone_dma_end)
+ return true;
+ else if (IS_ENABLED(CONFIG_ZONE_DMA32) && gfp & GFP_DMA32 &&
+ base > zone_dma_end && end <= zone_dma32_end)
+ return true;
+ else if (base > zone_dma32_end)
+ return true;
+
+ return false;
+}
+
static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
gfp_t gfp)
{
@@ -70,7 +104,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
do {
pool_size = 1 << (PAGE_SHIFT + order);
- if (dev_get_cma_area(NULL))
+ if (cma_in_zone(gfp))
page = dma_alloc_from_contiguous(NULL, 1 << order,
order, false);
else
--
2.27.0
Hi,
I have merged this to a 5.8 tree along with "dma-pool: Fix atomic pool
selection" and tested it in various ACPI/DT combinations, particularly
on the RPI4. It seems to be working fine.
So thanks for your time and effort clearing this up!
tested-by: Jeremy Linton <[email protected]>
On 7/10/20 9:10 AM, Nicolas Saenz Julienne wrote:
> There is no guarantee to CMA's placement, so allocating a zone specific
> atomic pool from CMA might return memory from a completely different
> memory zone. To get around this double check CMA's placement before
> allocating from it.
>
> Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp mask")
> Reported-by: Jeremy Linton <[email protected]>
> Signed-off-by: Nicolas Saenz Julienne <[email protected]>
> ---
>
> This is a code intensive alternative to "dma-pool: Do not allocate pool
> memory from CMA"[1].
>
> [1] https://lkml.org/lkml/2020/7/8/1108
>
> kernel/dma/pool.c | 36 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index 8cfa01243ed2..ccf3eeb77e00 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -3,6 +3,7 @@
> * Copyright (C) 2012 ARM Ltd.
> * Copyright (C) 2020 Google LLC
> */
> +#include <linux/cma.h>
> #include <linux/debugfs.h>
> #include <linux/dma-direct.h>
> #include <linux/dma-noncoherent.h>
> @@ -56,6 +57,39 @@ static void dma_atomic_pool_size_add(gfp_t gfp, size_t size)
> pool_size_kernel += size;
> }
>
> +static bool cma_in_zone(gfp_t gfp)
> +{
> + u64 zone_dma_end, zone_dma32_end;
> + phys_addr_t base, end;
> + unsigned long size;
> + struct cma *cma;
> +
> + cma = dev_get_cma_area(NULL);
> + if (!cma)
> + return false;
> +
> + size = cma_get_size(cma);
> + if (!size)
> + return false;
> + base = cma_get_base(cma) - memblock_start_of_DRAM();
> + end = base + size - 1;
> +
> + zone_dma_end = IS_ENABLED(CONFIG_ZONE_DMA) ? DMA_BIT_MASK(zone_dma_bits) : 0;
> + zone_dma32_end = IS_ENABLED(CONFIG_ZONE_DMA32) ? DMA_BIT_MASK(32) : 0;
> +
> + /* CMA can't cross zone boundaries, see cma_activate_area() */
> + if (IS_ENABLED(CONFIG_ZONE_DMA) && gfp & GFP_DMA &&
> + end <= zone_dma_end)
> + return true;
> + else if (IS_ENABLED(CONFIG_ZONE_DMA32) && gfp & GFP_DMA32 &&
> + base > zone_dma_end && end <= zone_dma32_end)
> + return true;
> + else if (base > zone_dma32_end)
> + return true;
> +
> + return false;
> +}
> +
> static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
> gfp_t gfp)
> {
> @@ -70,7 +104,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
> do {
> pool_size = 1 << (PAGE_SHIFT + order);
>
> - if (dev_get_cma_area(NULL))
> + if (cma_in_zone(gfp))
> page = dma_alloc_from_contiguous(NULL, 1 << order,
> order, false);
> else
>
Hi Chritoph,
On Fri, 2020-07-10 at 16:10 +0200, Nicolas Saenz Julienne wrote:
> There is no guarantee to CMA's placement, so allocating a zone specific
> atomic pool from CMA might return memory from a completely different
> memory zone. To get around this double check CMA's placement before
> allocating from it.
>
> Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp
> mask")
> Reported-by: Jeremy Linton <[email protected]>
> Signed-off-by: Nicolas Saenz Julienne <[email protected]>
> ---
>
> This is a code intensive alternative to "dma-pool: Do not allocate pool
> memory from CMA"[1].
I see you applied "dma-pool: Do not allocate pool memory from CMA" on your
tree. Do you want me to send a v2 of this patch taking that into account
targeting v5.9? or you'd rather just follow another approach?
Regards,
Nicolas
>
> [1] https://lkml.org/lkml/2020/7/8/1108
>
> kernel/dma/pool.c | 36 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
> index 8cfa01243ed2..ccf3eeb77e00 100644
> --- a/kernel/dma/pool.c
> +++ b/kernel/dma/pool.c
> @@ -3,6 +3,7 @@
> * Copyright (C) 2012 ARM Ltd.
> * Copyright (C) 2020 Google LLC
> */
> +#include <linux/cma.h>
> #include <linux/debugfs.h>
> #include <linux/dma-direct.h>
> #include <linux/dma-noncoherent.h>
> @@ -56,6 +57,39 @@ static void dma_atomic_pool_size_add(gfp_t gfp, size_t
> size)
> pool_size_kernel += size;
> }
>
> +static bool cma_in_zone(gfp_t gfp)
> +{
> + u64 zone_dma_end, zone_dma32_end;
> + phys_addr_t base, end;
> + unsigned long size;
> + struct cma *cma;
> +
> + cma = dev_get_cma_area(NULL);
> + if (!cma)
> + return false;
> +
> + size = cma_get_size(cma);
> + if (!size)
> + return false;
> + base = cma_get_base(cma) - memblock_start_of_DRAM();
> + end = base + size - 1;
> +
> + zone_dma_end = IS_ENABLED(CONFIG_ZONE_DMA) ? DMA_BIT_MASK(zone_dma_bits)
> : 0;
> + zone_dma32_end = IS_ENABLED(CONFIG_ZONE_DMA32) ? DMA_BIT_MASK(32) : 0;
> +
> + /* CMA can't cross zone boundaries, see cma_activate_area() */
> + if (IS_ENABLED(CONFIG_ZONE_DMA) && gfp & GFP_DMA &&
> + end <= zone_dma_end)
> + return true;
> + else if (IS_ENABLED(CONFIG_ZONE_DMA32) && gfp & GFP_DMA32 &&
> + base > zone_dma_end && end <= zone_dma32_end)
> + return true;
> + else if (base > zone_dma32_end)
> + return true;
> +
> + return false;
> +}
> +
> static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
> gfp_t gfp)
> {
> @@ -70,7 +104,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t
> pool_size,
> do {
> pool_size = 1 << (PAGE_SHIFT + order);
>
> - if (dev_get_cma_area(NULL))
> + if (cma_in_zone(gfp))
> page = dma_alloc_from_contiguous(NULL, 1 << order,
> order, false);
> else