* [PATCH v2 0/4] dma-pool: Fix atomic pool selection
@ 2020-07-14 12:39 Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 1/4] dma-direct: Provide function to check physical memory area validity Nicolas Saenz Julienne
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: Nicolas Saenz Julienne @ 2020-07-14 12:39 UTC (permalink / raw)
To: hch, linux-kernel
Cc: jeremy.linton, iommu, linux-rpi-kernel, David Rientjes, Robin Murphy
This is my attempt at fixing one of the regressions we've seen[1] after
the introduction of per-zone atomic pools.
This combined with "dma-pool: Do not allocate pool memory from CMA"[2]
should fix the boot issues on Jeremy's RPi4 setup.
[1] https://lkml.org/lkml/2020/7/2/974
[2] https://lkml.org/lkml/2020/7/8/1108
---
Changes since v1:
- Rebase into linus' master
Nicolas Saenz Julienne (4):
dma-direct: Provide function to check physical memory area validity
dma-pool: Get rid of dma_in_atomic_pool()
dma-pool: Introduce dma_guess_pool()
dma-pool: Make sure atomic pool suits device
include/linux/dma-direct.h | 1 +
kernel/dma/direct.c | 2 +-
kernel/dma/pool.c | 80 +++++++++++++++++++++++++-------------
3 files changed, 56 insertions(+), 27 deletions(-)
--
2.27.0
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^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 1/4] dma-direct: Provide function to check physical memory area validity
2020-07-14 12:39 [PATCH v2 0/4] dma-pool: Fix atomic pool selection Nicolas Saenz Julienne
@ 2020-07-14 12:39 ` Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 2/4] dma-pool: Get rid of dma_in_atomic_pool() Nicolas Saenz Julienne
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Nicolas Saenz Julienne @ 2020-07-14 12:39 UTC (permalink / raw)
To: hch, linux-kernel, Marek Szyprowski, Robin Murphy
Cc: iommu, linux-rpi-kernel, jeremy.linton
dma_coherent_ok() checks if a physical memory area fits a device's DMA
constraints.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
include/linux/dma-direct.h | 1 +
kernel/dma/direct.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 5184735a0fe8..ab2e20cba951 100644
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -69,6 +69,7 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size,
u64 dma_direct_get_required_mask(struct device *dev);
gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
u64 *phys_mask);
+bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size);
void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs);
void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 95866b647581..67f060b86a73 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -70,7 +70,7 @@ gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 dma_mask,
return 0;
}
-static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
+bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
{
return phys_to_dma_direct(dev, phys) + size - 1 <=
min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
--
2.27.0
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 2/4] dma-pool: Get rid of dma_in_atomic_pool()
2020-07-14 12:39 [PATCH v2 0/4] dma-pool: Fix atomic pool selection Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 1/4] dma-direct: Provide function to check physical memory area validity Nicolas Saenz Julienne
@ 2020-07-14 12:39 ` Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 3/4] dma-pool: Introduce dma_guess_pool() Nicolas Saenz Julienne
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Nicolas Saenz Julienne @ 2020-07-14 12:39 UTC (permalink / raw)
To: hch, linux-kernel, Marek Szyprowski, Robin Murphy
Cc: iommu, linux-rpi-kernel, jeremy.linton
The function is only used once and can be simplified to a one-liner.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
kernel/dma/pool.c | 11 +----------
1 file changed, 1 insertion(+), 10 deletions(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 39ca26fa41b5..318035e093fb 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -217,15 +217,6 @@ static inline struct gen_pool *dev_to_pool(struct device *dev)
return atomic_pool_kernel;
}
-static bool dma_in_atomic_pool(struct device *dev, void *start, size_t size)
-{
- struct gen_pool *pool = dev_to_pool(dev);
-
- if (unlikely(!pool))
- return false;
- return gen_pool_has_addr(pool, (unsigned long)start, size);
-}
-
void *dma_alloc_from_pool(struct device *dev, size_t size,
struct page **ret_page, gfp_t flags)
{
@@ -260,7 +251,7 @@ bool dma_free_from_pool(struct device *dev, void *start, size_t size)
{
struct gen_pool *pool = dev_to_pool(dev);
- if (!dma_in_atomic_pool(dev, start, size))
+ if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size))
return false;
gen_pool_free(pool, (unsigned long)start, size);
return true;
--
2.27.0
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 3/4] dma-pool: Introduce dma_guess_pool()
2020-07-14 12:39 [PATCH v2 0/4] dma-pool: Fix atomic pool selection Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 1/4] dma-direct: Provide function to check physical memory area validity Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 2/4] dma-pool: Get rid of dma_in_atomic_pool() Nicolas Saenz Julienne
@ 2020-07-14 12:39 ` Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 4/4] dma-pool: Make sure atomic pool suits device Nicolas Saenz Julienne
2020-07-15 7:12 ` [PATCH v2 0/4] dma-pool: Fix atomic pool selection Christoph Hellwig
4 siblings, 0 replies; 6+ messages in thread
From: Nicolas Saenz Julienne @ 2020-07-14 12:39 UTC (permalink / raw)
To: hch, linux-kernel, Marek Szyprowski, Robin Murphy
Cc: iommu, linux-rpi-kernel, jeremy.linton
dma-pool's dev_to_pool() creates the false impression that there is a
way to grantee a mapping between a device's DMA constraints and an
atomic pool. It tuns out it's just a guess, and the device might need to
use an atomic pool containing memory from a 'safer' (or lower) memory
zone.
To help mitigate this, introduce dma_guess_pool() which can be fed a
device's DMA constraints and atomic pools already known to be faulty, in
order for it to provide an better guess on which pool to use.
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
kernel/dma/pool.c | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 318035e093fb..5b9eaa2b498d 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -203,7 +203,7 @@ static int __init dma_atomic_pool_init(void)
}
postcore_initcall(dma_atomic_pool_init);
-static inline struct gen_pool *dev_to_pool(struct device *dev)
+static inline struct gen_pool *dma_guess_pool_from_device(struct device *dev)
{
u64 phys_mask;
gfp_t gfp;
@@ -217,10 +217,30 @@ static inline struct gen_pool *dev_to_pool(struct device *dev)
return atomic_pool_kernel;
}
+static inline struct gen_pool *dma_get_safer_pool(struct gen_pool *bad_pool)
+{
+ if (bad_pool == atomic_pool_kernel)
+ return atomic_pool_dma32 ? : atomic_pool_dma;
+
+ if (bad_pool == atomic_pool_dma32)
+ return atomic_pool_dma;
+
+ return NULL;
+}
+
+static inline struct gen_pool *dma_guess_pool(struct device *dev,
+ struct gen_pool *bad_pool)
+{
+ if (bad_pool)
+ return dma_get_safer_pool(bad_pool);
+
+ return dma_guess_pool_from_device(dev);
+}
+
void *dma_alloc_from_pool(struct device *dev, size_t size,
struct page **ret_page, gfp_t flags)
{
- struct gen_pool *pool = dev_to_pool(dev);
+ struct gen_pool *pool = dma_guess_pool(dev, NULL);
unsigned long val;
void *ptr = NULL;
@@ -249,7 +269,7 @@ void *dma_alloc_from_pool(struct device *dev, size_t size,
bool dma_free_from_pool(struct device *dev, void *start, size_t size)
{
- struct gen_pool *pool = dev_to_pool(dev);
+ struct gen_pool *pool = dma_guess_pool(dev, NULL);
if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size))
return false;
--
2.27.0
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 4/4] dma-pool: Make sure atomic pool suits device
2020-07-14 12:39 [PATCH v2 0/4] dma-pool: Fix atomic pool selection Nicolas Saenz Julienne
` (2 preceding siblings ...)
2020-07-14 12:39 ` [PATCH v2 3/4] dma-pool: Introduce dma_guess_pool() Nicolas Saenz Julienne
@ 2020-07-14 12:39 ` Nicolas Saenz Julienne
2020-07-15 7:12 ` [PATCH v2 0/4] dma-pool: Fix atomic pool selection Christoph Hellwig
4 siblings, 0 replies; 6+ messages in thread
From: Nicolas Saenz Julienne @ 2020-07-14 12:39 UTC (permalink / raw)
To: hch, linux-kernel, Marek Szyprowski, Robin Murphy, David Rientjes
Cc: iommu, linux-rpi-kernel, jeremy.linton
When allocating DMA memory from a pool, the core can only guess which
atomic pool will fit a device's constraints. If it doesn't, get a safer
atomic pool and try again.
Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp mask")
Reported-by: Jeremy Linton <jeremy.linton@arm.com>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
---
Changes since v1:
- Rebase to linus' master
kernel/dma/pool.c | 57 ++++++++++++++++++++++++++++++-----------------
1 file changed, 37 insertions(+), 20 deletions(-)
diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c
index 5b9eaa2b498d..d48d9acb585f 100644
--- a/kernel/dma/pool.c
+++ b/kernel/dma/pool.c
@@ -240,39 +240,56 @@ static inline struct gen_pool *dma_guess_pool(struct device *dev,
void *dma_alloc_from_pool(struct device *dev, size_t size,
struct page **ret_page, gfp_t flags)
{
- struct gen_pool *pool = dma_guess_pool(dev, NULL);
- unsigned long val;
+ struct gen_pool *pool = NULL;
+ unsigned long val = 0;
void *ptr = NULL;
-
- if (!pool) {
- WARN(1, "%pGg atomic pool not initialised!\n", &flags);
- return NULL;
+ phys_addr_t phys;
+
+ while (1) {
+ pool = dma_guess_pool(dev, pool);
+ if (!pool) {
+ WARN(1, "Failed to get suitable pool for %s\n",
+ dev_name(dev));
+ break;
+ }
+
+ val = gen_pool_alloc(pool, size);
+ if (!val)
+ continue;
+
+ phys = gen_pool_virt_to_phys(pool, val);
+ if (dma_coherent_ok(dev, phys, size))
+ break;
+
+ gen_pool_free(pool, val, size);
+ val = 0;
}
- val = gen_pool_alloc(pool, size);
- if (likely(val)) {
- phys_addr_t phys = gen_pool_virt_to_phys(pool, val);
+ if (val) {
*ret_page = pfn_to_page(__phys_to_pfn(phys));
ptr = (void *)val;
memset(ptr, 0, size);
- } else {
- WARN_ONCE(1, "DMA coherent pool depleted, increase size "
- "(recommended min coherent_pool=%zuK)\n",
- gen_pool_size(pool) >> 9);
+
+ if (gen_pool_avail(pool) < atomic_pool_size)
+ schedule_work(&atomic_pool_work);
}
- if (gen_pool_avail(pool) < atomic_pool_size)
- schedule_work(&atomic_pool_work);
return ptr;
}
bool dma_free_from_pool(struct device *dev, void *start, size_t size)
{
- struct gen_pool *pool = dma_guess_pool(dev, NULL);
+ struct gen_pool *pool = NULL;
- if (!pool || !gen_pool_has_addr(pool, (unsigned long)start, size))
- return false;
- gen_pool_free(pool, (unsigned long)start, size);
- return true;
+ while (1) {
+ pool = dma_guess_pool(dev, pool);
+ if (!pool)
+ return false;
+
+ if (gen_pool_has_addr(pool, (unsigned long)start, size)) {
+ gen_pool_free(pool, (unsigned long)start, size);
+ return true;
+ }
+ }
}
--
2.27.0
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^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 0/4] dma-pool: Fix atomic pool selection
2020-07-14 12:39 [PATCH v2 0/4] dma-pool: Fix atomic pool selection Nicolas Saenz Julienne
` (3 preceding siblings ...)
2020-07-14 12:39 ` [PATCH v2 4/4] dma-pool: Make sure atomic pool suits device Nicolas Saenz Julienne
@ 2020-07-15 7:12 ` Christoph Hellwig
4 siblings, 0 replies; 6+ messages in thread
From: Christoph Hellwig @ 2020-07-15 7:12 UTC (permalink / raw)
To: Nicolas Saenz Julienne
Cc: linux-kernel, jeremy.linton, iommu, linux-rpi-kernel,
David Rientjes, Robin Murphy, hch
On Tue, Jul 14, 2020 at 02:39:24PM +0200, Nicolas Saenz Julienne wrote:
> This is my attempt at fixing one of the regressions we've seen[1] after
> the introduction of per-zone atomic pools.
>
> This combined with "dma-pool: Do not allocate pool memory from CMA"[2]
> should fix the boot issues on Jeremy's RPi4 setup.
I've applied the series as well as that patch to the dma-mapping tree,
thanks.
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2020-07-14 12:39 [PATCH v2 0/4] dma-pool: Fix atomic pool selection Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 1/4] dma-direct: Provide function to check physical memory area validity Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 2/4] dma-pool: Get rid of dma_in_atomic_pool() Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 3/4] dma-pool: Introduce dma_guess_pool() Nicolas Saenz Julienne
2020-07-14 12:39 ` [PATCH v2 4/4] dma-pool: Make sure atomic pool suits device Nicolas Saenz Julienne
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