[RFC PATCH v2 03/21] mm: Allow DMA mapping of pages which are not online
From: Jonathan Lemon <hidden>
Date: 2020-07-27 22:45:28
Subsystem:
dma mapping helpers, memory management - core, memory management - mglru (multi-gen lru), the rest · Maintainers:
Marek Szyprowski, Andrew Morton, David Hildenbrand, Linus Torvalds
Change the system RAM check from 'valid' to 'online', so dummy pages which refer to external DMA resources can be mapped. Signed-off-by: Jonathan Lemon <redacted> --- include/linux/dma-mapping.h | 4 ++-- include/linux/mmzone.h | 7 +++++++ 2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index a33ed3954ed4..e9b1a8431568 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h@@ -348,8 +348,8 @@ static inline dma_addr_t dma_map_resource(struct device *dev, BUG_ON(!valid_dma_direction(dir)); - /* Don't allow RAM to be mapped */ - if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr)))) + /* Don't allow online RAM to be mapped */ + if (WARN_ON_ONCE(pfn_online(PHYS_PFN(phys_addr)))) return DMA_MAPPING_ERROR; if (dma_is_direct(ops))
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f6f884970511..d0c6fc553304 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h@@ -1348,6 +1348,13 @@ static inline unsigned long next_present_section_nr(unsigned long section_nr) return -1; } +static inline int pfn_online(unsigned long pfn) +{ + if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) + return 0; + return online_section(__nr_to_section(pfn_to_section_nr(pfn))); +} + /* * These are _only_ used during initialisation, therefore they * can use __initdata ... They could have names to indicate
--
2.24.1