linux/drivers/dma-buf/Kconfig, branch master

dma-buf: Always build with DMABUF_MOVE_NOTIFY

2026-01-27T09:45:11Z

DMABUF_MOVE_NOTIFY was introduced in 2018 and has been marked as experimental and disabled by default ever since. Six years later, all new importers implement this callback. It is therefore reasonable to drop CONFIG_DMABUF_MOVE_NOTIFY and always build DMABUF with support for it enabled. Suggested-by: Christian König Signed-off-by: Leon Romanovsky Reviewed-by: Christian König Link: https://lore.kernel.org/r/20260124-dmabuf-revoke-v5-3-f98fca917e96@nvidia.com Signed-off-by: Christian König

dma-buf: Remove DMA-BUF sysfs stats

2026-01-19T13:40:01Z

Commit bdb8d06dfefd ("dmabuf: Add the capability to expose DMA-BUF stats in sysfs") added dmabuf statistics to sysfs in 2021 under CONFIG_DMABUF_SYSFS_STATS. After being used in production, performance problems were discovered leading to its deprecation in 2022 in commit e0a9f1fe206a ("dma-buf: deprecate DMABUF_SYSFS_STATS"). Some of the problems with this interface were discussed in my LPC 2025 talk. [1][2] Android was probably the last user of the interface, which has since been migrated to use the dmabuf BPF iterator [3] to obtain the same information more cheaply. As promised in that series, now that the longterm stable 6.18 kernel has been released let's remove the sysfs dmabuf statistics from the kernel. [1] https://www.youtube.com/watch?v=D83qygudq9c [2] https://lpc.events/event/19/contributions/2118/ [3] https://lore.kernel.org/all/20250522230429.941193-1-tjmercier@google.com/ Signed-off-by: T.J. Mercier Reviewed-by: Christian König Signed-off-by: Sumit Semwal Link: https://patch.msgid.link/20260116190517.3268458-1-tjmercier@google.com

dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels

2025-12-08T15:39:09Z

The overhead of enforcing the DMA-buf rules for importers is now so low that it safe to enable it by default on DEBUG kernels. This will hopefully result in fixing more issues in importers. Signed-off-by: Christian König Reviewed-by: Michael J. Ruhl Link: https://lore.kernel.org/r/20251205130604.1582-2-christian.koenig@amd.com

Revert "udmabuf: fix vmap_udmabuf error page set"

2025-05-16T04:54:51Z

This reverts commit 18d7de823b7150344d242c3677e65d68c5271b04. We cannot use vmap_pfn() in vmap_udmabuf() as it would fail the pfn_valid() check in vmap_pfn_apply(). This is because vmap_pfn() is intended to be used for mapping non-struct-page memory such as PCIe BARs. Since, udmabuf mostly works with pages/folios backed by shmem/hugetlbfs/THP, vmap_pfn() is not the right tool or API to invoke for implementing vmap. Signed-off-by: Huan Yang Suggested-by: Vivek Kasireddy Reported-by: Bingbu Cao Closes: https://lore.kernel.org/dri-devel/eb7e0137-3508-4287-98c4-816c5fd98e10@vivo.com/T/#mbda4f64a3532b32e061f4e8763bc8e307bea3ca8 Acked-by: Vivek Kasireddy Signed-off-by: Vivek Kasireddy Link: https://lore.kernel.org/r/20250428073831.19942-2-link@vivo.com

udmabuf: fix vmap_udmabuf error page set

2024-09-20T21:07:32Z

Currently vmap_udmabuf set page's array by each folio. But, ubuf->folios is only contain's the folio's head page. That mean we repeatedly mapped the folio head page to the vmalloc area. Due to udmabuf can use hugetlb, if HVO enabled, tail page may not exist, so, we can't use page array to map, instead, use pfn array. By this, we removed page usage in udmabuf totally. Fixes: 5e72b2b41a21 ("udmabuf: convert udmabuf driver to use folios") Suggested-by: Vivek Kasireddy Signed-off-by: Huan Yang Acked-by: Vivek Kasireddy Signed-off-by: Vivek Kasireddy Link: https://patchwork.freedesktop.org/patch/msgid/20240918025238.2957823-4-link@vivo.com

udmabuf: add CONFIG_MMU dependency

2024-07-12T22:52:10Z

There is no !CONFIG_MMU version of vmf_insert_pfn(): arm-linux-gnueabi-ld: drivers/dma-buf/udmabuf.o: in function `udmabuf_vm_fault': udmabuf.c:(.text+0xaa): undefined reference to `vmf_insert_pfn' Link: https://lkml.kernel.org/r/20240624063952.1572359-5-vivek.kasireddy@intel.com Signed-off-by: Arnd Bergmann Acked-by: David Hildenbrand Acked-by: Vivek Kasireddy Cc: Christoph Hellwig Cc: Christoph Hellwig Cc: Daniel Vetter Cc: Dave Airlie Cc: Dongwon Kim Cc: Gerd Hoffmann Cc: Hugh Dickins Cc: Jason Gunthorpe Cc: Junxiao Chang Cc: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Oscar Salvador Cc: Peter Xu Cc: Shuah Khan Signed-off-by: Andrew Morton

dma-buf: deprecate DMABUF_SYSFS_STATS

2022-06-23T08:51:43Z

Add a warning that this UAPI wasn't such a good idea and shouldn't be used by anybody. That should give us a better chance to remove it at some point and prevents others from running into the same issues. Signed-off-by: Christian König Reviewed-by: T.J. Mercier Link: https://patchwork.freedesktop.org/patch/msgid/20220617085702.4298-1-christian.koenig@amd.com

dma-buf: DMABUF_SYSFS_STATS should depend on DMA_SHARED_BUFFER

2021-09-07T07:12:21Z

DMA-BUF sysfs statistics are an option of DMA-BUF. It does not make much sense to bother the user with a question about DMA-BUF sysfs statistics if DMA-BUF itself is not enabled. Worse, enabling the statistics enables the feature. Fixes: bdb8d06dfefd666d ("dmabuf: Add the capability to expose DMA-BUF stats in sysfs") Signed-off-by: Geert Uytterhoeven Signed-off-by: Sumit Semwal Link: https://patchwork.freedesktop.org/patch/msgid/20210902124913.2698760-4-geert@linux-m68k.org

dma-buf: DMABUF_DEBUG should depend on DMA_SHARED_BUFFER

2021-09-07T07:12:21Z

DMA-BUF debug checks are an option of DMA-BUF. Enabling DMABUF_DEBUG without DMA_SHARED_BUFFER does not have any impact, as drivers/dma-buf/ is not entered during the build when DMA_SHARED_BUFFER is disabled. Fixes: 84335675f2223cbd ("dma-buf: Add debug option") Signed-off-by: Geert Uytterhoeven Signed-off-by: Sumit Semwal Link: https://patchwork.freedesktop.org/patch/msgid/20210902124913.2698760-3-geert@linux-m68k.org

dma-buf: DMABUF_MOVE_NOTIFY should depend on DMA_SHARED_BUFFER

2021-09-02T14:49:11Z

Move notify between drivers is an option of DMA-BUF. Enabling DMABUF_MOVE_NOTIFY without DMA_SHARED_BUFFER does not have any impact, as drivers/dma-buf/ is not entered during the build when DMA_SHARED_BUFFER is disabled. Fixes: bb42df4662a44765 ("dma-buf: add dynamic DMA-buf handling v15") Signed-off-by: Geert Uytterhoeven Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210902124913.2698760-2-geert@linux-m68k.org