* [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous()
@ 2019-07-26 19:34 Nicolin Chen
2019-07-26 19:34 ` [PATCH v2 1/2] dma-contiguous: do not overwrite align in dma_alloc_contiguous() Nicolin Chen
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Nicolin Chen @ 2019-07-26 19:34 UTC (permalink / raw)
To: dafna.hirschfeld, hch, m.szyprowski, robin.murphy; +Cc: iommu, linux-kernel
There are two obvious bugs in these two functions. So having
two patches to fix them.
Changlog
v1->v2:
* PATCH-1: Confine cma_align inside the if-condition.
* PATCH-1: Updated commit message to be precise for the corner case.
* PATCH-2: Added Reviewed-by from Christoph.
Nicolin Chen (2):
dma-contiguous: do not overwrite align in dma_alloc_contiguous()
dma-contiguous: page-align the size in dma_free_contiguous()
kernel/dma/contiguous.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--
2.17.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v2 1/2] dma-contiguous: do not overwrite align in dma_alloc_contiguous()
2019-07-26 19:34 [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous() Nicolin Chen
@ 2019-07-26 19:34 ` Nicolin Chen
2019-07-26 19:34 ` [PATCH v2 2/2] dma-contiguous: page-align the size in dma_free_contiguous() Nicolin Chen
2019-07-29 6:50 ` [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous() Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Nicolin Chen @ 2019-07-26 19:34 UTC (permalink / raw)
To: dafna.hirschfeld, hch, m.szyprowski, robin.murphy; +Cc: iommu, linux-kernel
The dma_alloc_contiguous() limits align at CONFIG_CMA_ALIGNMENT for
cma_alloc() however it does not restore it for the fallback routine.
This will result in a size mismatch between the allocation and free
when running into the fallback routines after cma_alloc() fails, if
the align is larger than CONFIG_CMA_ALIGNMENT.
This patch adds a cma_align to take care of cma_alloc() and prevent
the align from being overwritten.
Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers")
Reported-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
kernel/dma/contiguous.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index bfc0c17f2a3d..ea8259f53eda 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -243,8 +243,9 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
/* CMA can be used only in the context which permits sleeping */
if (cma && gfpflags_allow_blocking(gfp)) {
- align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
- page = cma_alloc(cma, count, align, gfp & __GFP_NOWARN);
+ size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
+
+ page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
}
/* Fallback allocation of normal pages */
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2 2/2] dma-contiguous: page-align the size in dma_free_contiguous()
2019-07-26 19:34 [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous() Nicolin Chen
2019-07-26 19:34 ` [PATCH v2 1/2] dma-contiguous: do not overwrite align in dma_alloc_contiguous() Nicolin Chen
@ 2019-07-26 19:34 ` Nicolin Chen
2019-07-29 6:50 ` [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous() Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Nicolin Chen @ 2019-07-26 19:34 UTC (permalink / raw)
To: dafna.hirschfeld, hch, m.szyprowski, robin.murphy; +Cc: iommu, linux-kernel
According to the original dma_direct_alloc_pages() code:
{
unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
if (!dma_release_from_contiguous(dev, page, count))
__free_pages(page, get_order(size));
}
The count parameter for dma_release_from_contiguous() was page
aligned before the right-shifting operation, while the new API
dma_free_contiguous() forgets to have PAGE_ALIGN() at the size.
So this patch simply adds it to prevent any corner case.
Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers")
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
kernel/dma/contiguous.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index ea8259f53eda..2bd410f934b3 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -267,7 +267,8 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
*/
void dma_free_contiguous(struct device *dev, struct page *page, size_t size)
{
- if (!cma_release(dev_get_cma_area(dev), page, size >> PAGE_SHIFT))
+ if (!cma_release(dev_get_cma_area(dev), page,
+ PAGE_ALIGN(size) >> PAGE_SHIFT))
__free_pages(page, get_order(size));
}
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous()
2019-07-26 19:34 [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous() Nicolin Chen
2019-07-26 19:34 ` [PATCH v2 1/2] dma-contiguous: do not overwrite align in dma_alloc_contiguous() Nicolin Chen
2019-07-26 19:34 ` [PATCH v2 2/2] dma-contiguous: page-align the size in dma_free_contiguous() Nicolin Chen
@ 2019-07-29 6:50 ` Christoph Hellwig
2 siblings, 0 replies; 4+ messages in thread
From: Christoph Hellwig @ 2019-07-29 6:50 UTC (permalink / raw)
To: Nicolin Chen
Cc: dafna.hirschfeld, hch, m.szyprowski, robin.murphy, iommu, linux-kernel
Thanks,
applied to the dma-mapping for-linus tree.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-07-26 19:34 [PATCH v2 0/2] dma-contiguous: two bug fixes for dma_{alloc,free}_contiguous() Nicolin Chen
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2019-07-26 19:34 ` [PATCH v2 2/2] dma-contiguous: page-align the size in dma_free_contiguous() Nicolin Chen
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