Hi Christoph,
On 11.11.2021 07:50, Christoph Hellwig wrote:
> Add a helper to check if a potentially blocking operation should
> dip into the atomic pools.
>
> Signed-off-by: Christoph Hellwig <[email protected]>
> Reviewed-by: Robin Murphy <[email protected]>
> ---
> kernel/dma/direct.c | 18 ++++++++++++------
> 1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 924937c54e8ab..d0a317ed8f029 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -156,6 +156,15 @@ static struct page *__dma_direct_alloc_pages(struct
> device *dev, size_t size,
> return page;
> }
>
> +/*
> + * Check if a potentially blocking operations needs to dip into the atomic
> + * pools for the given device/gfp.
> + */
> +static bool dma_direct_use_pool(struct device *dev, gfp_t gfp)
> +{
> + return gfpflags_allow_blocking(gfp) && !is_swiotlb_for_alloc(dev);
This should be:
return !gfpflags_allow_blocking(gfp) && !is_swiotlb_for_alloc(dev);
otherwise all dma allocations fail badly on ARM64, what happens on today's
linux-next (plenty of "Failed to get suitable pool for XYZ" messages).
Do you want me to send a fixup patch or would you simply fix it in your tree?
> +}
> +
> static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
> dma_addr_t *dma_handle, gfp_t gfp)
> {
> @@ -235,8 +244,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
> */
> remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP);
> if (remap) {
> - if (!gfpflags_allow_blocking(gfp) &&
> - !is_swiotlb_for_alloc(dev))
> + if (dma_direct_use_pool(dev, gfp))
> return dma_direct_alloc_from_pool(dev, size,
> dma_handle, gfp);
> } else {
> @@ -250,8 +258,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
> * Decrypting memory may block, so allocate the memory from the atomic
> * pools if we can't block.
> */
> - if (force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
> - !is_swiotlb_for_alloc(dev))
> + if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))
> return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
>
> /* we always manually zero the memory once we are done */
> @@ -360,8 +367,7 @@ struct page *dma_direct_alloc_pages(struct device *dev,
> size_t size,
> struct page *page;
> void *ret;
>
> - if (force_dma_unencrypted(dev) && !gfpflags_allow_blocking(gfp) &&
> - !is_swiotlb_for_alloc(dev))
> + if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))
> return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
>
> page = __dma_direct_alloc_pages(dev, size, gfp);
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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