Linaro-mm-sig January 2026

linaro-mm-sig@lists.linaro.org

44 participants
35 discussions

[PATCH v2 0/4] dma-buf: document revoke mechanism to invalidate shared buffers

by Leon Romanovsky

Changelog: v2: * Changed series to document the revoke semantics instead of implementing it. v1: https://patch.msgid.link/20260111-dmabuf-revoke-v1-0-fb4bcc8c259b@nvidia.com ------------------------------------------------------------------------- This series documents a dma-buf “revoke” mechanism: to allow a dma-buf exporter to explicitly invalidate (“kill”) a shared buffer after it has been distributed to importers, so that further CPU and device access is prevented and importers reliably observe failure. The change in this series is to properly document and use existing core “revoked” state on the dma-buf object and a corresponding exporter-triggered revoke operation. Once a dma-buf is revoked, new access paths are blocked so that attempts to DMA-map, vmap, or mmap the buffer fail in a consistent way. Thanks Cc: linux-media(a)vger.kernel.org Cc: dri-devel(a)lists.freedesktop.org Cc: linaro-mm-sig(a)lists.linaro.org Cc: linux-kernel(a)vger.kernel.org Cc: amd-gfx(a)lists.freedesktop.org Cc: virtualization(a)lists.linux.dev Cc: intel-xe(a)lists.freedesktop.org Cc: linux-rdma(a)vger.kernel.org Cc: iommu(a)lists.linux.dev Cc: kvm(a)vger.kernel.org To: Sumit Semwal <sumit.semwal(a)linaro.org> To: Christian König <christian.koenig(a)amd.com> To: Alex Deucher <alexander.deucher(a)amd.com> To: David Airlie <airlied(a)gmail.com> To: Simona Vetter <simona(a)ffwll.ch> To: Gerd Hoffmann <kraxel(a)redhat.com> To: Dmitry Osipenko <dmitry.osipenko(a)collabora.com> To: Gurchetan Singh <gurchetansingh(a)chromium.org> To: Chia-I Wu <olvaffe(a)gmail.com> To: Maarten Lankhorst <maarten.lankhorst(a)linux.intel.com> To: Maxime Ripard <mripard(a)kernel.org> To: Thomas Zimmermann <tzimmermann(a)suse.de> To: Lucas De Marchi <lucas.demarchi(a)intel.com> To: Thomas Hellström <thomas.hellstrom(a)linux.intel.com> To: Rodrigo Vivi <rodrigo.vivi(a)intel.com> To: Jason Gunthorpe <jgg(a)ziepe.ca> To: Leon Romanovsky <leon(a)kernel.org> To: Kevin Tian <kevin.tian(a)intel.com> To: Joerg Roedel <joro(a)8bytes.org> To: Will Deacon <will(a)kernel.org> To: Robin Murphy <robin.murphy(a)arm.com> To: Alex Williamson <alex(a)shazbot.org> --- Leon Romanovsky (4): dma-buf: Rename .move_notify() callback to a clearer identifier dma-buf: Document revoke semantics iommufd: Require DMABUF revoke semantics vfio: Add pinned interface to perform revoke semantics drivers/dma-buf/dma-buf.c | 6 +++--- drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 4 ++-- drivers/gpu/drm/virtio/virtgpu_prime.c | 2 +- drivers/gpu/drm/xe/tests/xe_dma_buf.c | 6 +++--- drivers/gpu/drm/xe/xe_dma_buf.c | 2 +- drivers/infiniband/core/umem_dmabuf.c | 4 ++-- drivers/infiniband/hw/mlx5/mr.c | 2 +- drivers/iommu/iommufd/pages.c | 11 +++++++++-- drivers/vfio/pci/vfio_pci_dmabuf.c | 16 ++++++++++++++++ include/linux/dma-buf.h | 25 ++++++++++++++++++++++--- 10 files changed, 60 insertions(+), 18 deletions(-) --- base-commit: 9ace4753a5202b02191d54e9fdf7f9e3d02b85eb change-id: 20251221-dmabuf-revoke-b90ef16e4236 Best regards, -- Leon Romanovsky <leonro(a)nvidia.com>

3 months

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by Seven

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3 months

Re: types: reuse common phys_vec type instead of DMABUF open‑coded variant

by Jens Axboe

On 1/16/26 10:14 AM, Alex Williamson wrote: > On Wed, 14 Jan 2026 14:18:19 +0200 > Leon Romanovsky <leon(a)kernel.org> wrote: > >> On Wed, Jan 07, 2026 at 11:14:14AM +0200, Leon Romanovsky wrote: >>> From: Leon Romanovsky <leonro(a)nvidia.com> >>> >>> After commit fcf463b92a08 ("types: move phys_vec definition to common header"), >>> we can use the shared phys_vec type instead of the DMABUF?specific >>> dma_buf_phys_vec, which duplicated the same structure and semantics. >>> >>> Signed-off-by: Leon Romanovsky <leonro(a)nvidia.com> >>> --- >>> Alex, >>> >>> According to diffstat, VFIO is the subsystem with the largest set of changes, >>> so it would be great if you could take it through your tree. >>> >>> The series is based on the for-7.0/blk-pvec shared branch from Jens: >>> https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git/log/?h=for-… >>> >>> Thanks >>> --- >> >> Alex, >> >> Could you please move this patch forward? We have the RDMA series [1] that >> depends on this rename, and I would like to base it on the shared branch. >> >> [1] https://lore.kernel.org/all/20260108-dmabuf-export-v1-0-6d47d46580d3@nvidia… > > I tried to ping Jens regarding why the branch with this code hasn't > been merged into their for-next branch, maybe you have more traction. > Thanks, I get a lot of emails, and pings inside existing series don't always get seen... Usually better to do a forward for a ping, then it's a lot more likely to get seen sooner. -- Jens Axboe

3 months

Re: types: reuse common phys_vec type instead of DMABUF open‑coded variant

by Leon Romanovsky

On Fri, Jan 16, 2026 at 10:14:55AM -0700, Alex Williamson wrote: > On Wed, 14 Jan 2026 14:18:19 +0200 > Leon Romanovsky <leon(a)kernel.org> wrote: > > > On Wed, Jan 07, 2026 at 11:14:14AM +0200, Leon Romanovsky wrote: > > > From: Leon Romanovsky <leonro(a)nvidia.com> > > > > > > After commit fcf463b92a08 ("types: move phys_vec definition to common header"), > > > we can use the shared phys_vec type instead of the DMABUF‑specific > > > dma_buf_phys_vec, which duplicated the same structure and semantics. > > > > > > Signed-off-by: Leon Romanovsky <leonro(a)nvidia.com> > > > --- > > > Alex, > > > > > > According to diffstat, VFIO is the subsystem with the largest set of changes, > > > so it would be great if you could take it through your tree. > > > > > > The series is based on the for-7.0/blk-pvec shared branch from Jens: > > > https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git/log/?h=for-… > > > > > > Thanks > > > --- > > > > Alex, > > > > Could you please move this patch forward? We have the RDMA series [1] that > > depends on this rename, and I would like to base it on the shared branch. > > > > [1] https://lore.kernel.org/all/20260108-dmabuf-export-v1-0-6d47d46580d3@nvidia… > > I tried to ping Jens regarding why the branch with this code hasn't > been merged into their for-next branch, maybe you have more traction. It is in block/for-next now, commit df73d3c618b4 ("Merge branch 'for-7.0/blk-pvec' into for-7.0/block". Thanks > Thanks, > > Alex >

3 months

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3 months

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3 months

Independence for dma_fences! v5

by Christian König

Hi everyone, dma_fences have ever lived under the tyranny dictated by the module lifetime of their issuer, leading to crashes should anybody still holding a reference to a dma_fence when the module of the issuer was unloaded. The basic problem is that when buffer are shared between drivers dma_fence objects can leak into external drivers and stay there even after they are signaled. The dma_resv object for example only lazy releases dma_fences. So what happens is that when the module who originally created the dma_fence unloads the dma_fence_ops function table becomes unavailable as well and so any attempt to release the fence crashes the system. Previously various approaches have been discussed, including changing the locking semantics of the dma_fence callbacks (by me) as well as using the drm scheduler as intermediate layer (by Sima) to disconnect dma_fences from their actual users, but none of them are actually solving all problems. Tvrtko did some really nice prerequisite work by protecting the returned strings of the dma_fence_ops by RCU. This way dma_fence creators where able to just wait for an RCU grace period after fence signaling before they could be save to free those data structures. Now this patch set here goes a step further and protects the whole dma_fence_ops structure by RCU, so that after the fence signals the pointer to the dma_fence_ops is set to NULL when there is no wait nor release callback given. All functionality which use the dma_fence_ops reference are put inside an RCU critical section, except for the deprecated issuer specific wait and of course the optional release callback. Additional to the RCU changes the lock protecting the dma_fence state previously had to be allocated external. This set here now changes the functionality to make that external lock optional and allows dma_fences to use an inline lock and be self contained. v4: Rebases the whole set on upstream changes, especially the cleanup from Philip in patch "drm/amdgpu: independence for the amdkfd_fence!". Adding two patches which brings the DMA-fence self tests up to date. The first selftest changes removes the mock_wait and so actually starts testing the default behavior instead of some hacky implementation in the test. This one got upstreamed independent of this set. The second drops the mock_fence as well and tests the new RCU and inline spinlock functionality. v5: Rebase on top of drm-misc-next instead of drm-tip, leave out all driver changes for now since those should go through the driver specific paths anyway. Address a few more review comments, especially some rebase mess and typos. And finally fix one more bug found by AMDs CI system. Especially the first patch still needs a Reviewed-by, apart from that I think I've addressed all review comments and problems. Please review and comment, Christian.

3 months

[PATCH v2 0/2] dma-buf: system_heap: account for system heap allocation in memcg

by Eric Chanudet

Capture dmabuf system heap allocations in memcg following prior conversations[1][2]. Disable this behavior by default unless configured by "dma_heap.mem_accounting" module parameter. [1] https://lore.kernel.org/dri-devel/Z-5GZ3kJDbhgVBPG@phenom.ffwll.local/ [2] https://lore.kernel.org/all/CABdmKX2_UOENujpW0dXe0Z0x+4V3onfGDmHf1DMOXfDha6… Changes in v2: - Add a module parameter to enable dma-buf cgroup accounting, disabled by default. - Split system_heap logic in its own commit. - Link to v1: https://lore.kernel.org/lkml/20251211193106.755485-2-echanude@redhat.com/ Signed-off-by: Eric Chanudet <echanude(a)redhat.com> --- Eric Chanudet (2): dma-buf: heaps: add parameter to account allocations using cgroup dma-buf: system_heap: account for system heap allocation in memcg drivers/dma-buf/dma-heap.c | 5 +++++ drivers/dma-buf/heaps/system_heap.c | 9 +++++++-- 2 files changed, 12 insertions(+), 2 deletions(-) --- base-commit: b71e635feefc852405b14620a7fc58c4c80c0f73 change-id: 20260102-dmabuf-heap-system-memcg-c86a381d663a Best regards, -- Eric Chanudet <echanude(a)redhat.com>

3 months

[PATCH] mm/vmalloc: map contiguous pages in batches for vmap() whenever possible

by Barry Song

From: Barry Song <v-songbaohua(a)oppo.com> In many cases, the pages passed to vmap() may include high-order pages allocated with __GFP_COMP flags. For example, the systemheap often allocates pages in descending order: order 8, then 4, then 0. Currently, vmap() iterates over every page individually—even pages inside a high-order block are handled one by one. This patch detects high-order pages and maps them as a single contiguous block whenever possible. An alternative would be to implement a new API, vmap_sg(), but that change seems to be large in scope. When vmapping a 128MB dma-buf using the systemheap, this patch makes system_heap_do_vmap() roughly 17× faster. W/ patch: [ 10.404769] system_heap_do_vmap took 2494000 ns [ 12.525921] system_heap_do_vmap took 2467008 ns [ 14.517348] system_heap_do_vmap took 2471008 ns [ 16.593406] system_heap_do_vmap took 2444000 ns [ 19.501341] system_heap_do_vmap took 2489008 ns W/o patch: [ 7.413756] system_heap_do_vmap took 42626000 ns [ 9.425610] system_heap_do_vmap took 42500992 ns [ 11.810898] system_heap_do_vmap took 42215008 ns [ 14.336790] system_heap_do_vmap took 42134992 ns [ 16.373890] system_heap_do_vmap took 42750000 ns Cc: David Hildenbrand <david(a)kernel.org> Cc: Uladzislau Rezki <urezki(a)gmail.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: John Stultz <jstultz(a)google.com> Cc: Maxime Ripard <mripard(a)kernel.org> Tested-by: Tangquan Zheng <zhengtangquan(a)oppo.com> Signed-off-by: Barry Song <v-songbaohua(a)oppo.com> --- * diff with rfc: Many code refinements based on David's suggestions, thanks! Refine comment and changelog according to Uladzislau, thanks! rfc link: https://lore.kernel.org/linux-mm/20251122090343.81243-1-21cnbao@gmail.com/ mm/vmalloc.c | 45 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 41dd01e8430c..8d577767a9e5 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -642,6 +642,29 @@ static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end, return err; } +static inline int get_vmap_batch_order(struct page **pages, + unsigned int stride, unsigned int max_steps, unsigned int idx) +{ + int nr_pages = 1; + + /* + * Currently, batching is only supported in vmap_pages_range + * when page_shift == PAGE_SHIFT. + */ + if (stride != 1) + return 0; + + nr_pages = compound_nr(pages[idx]); + if (nr_pages == 1) + return 0; + if (max_steps < nr_pages) + return 0; + + if (num_pages_contiguous(&pages[idx], nr_pages) == nr_pages) + return compound_order(pages[idx]); + return 0; +} + /* * vmap_pages_range_noflush is similar to vmap_pages_range, but does not * flush caches. @@ -655,23 +678,33 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, unsigned int page_shift) { unsigned int i, nr = (end - addr) >> PAGE_SHIFT; + unsigned int stride; WARN_ON(page_shift < PAGE_SHIFT); + /* + * For vmap(), users may allocate pages from high orders down to + * order 0, while always using PAGE_SHIFT as the page_shift. + * We first check whether the initial page is a compound page. If so, + * there may be an opportunity to batch multiple pages together. + */ if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || - page_shift == PAGE_SHIFT) + (page_shift == PAGE_SHIFT && !PageCompound(pages[0]))) return vmap_small_pages_range_noflush(addr, end, prot, pages); - for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) { - int err; + stride = 1U << (page_shift - PAGE_SHIFT); + for (i = 0; i < nr; ) { + int err, order; - err = vmap_range_noflush(addr, addr + (1UL << page_shift), + order = get_vmap_batch_order(pages, stride, nr - i, i); + err = vmap_range_noflush(addr, addr + (1UL << (page_shift + order)), page_to_phys(pages[i]), prot, - page_shift); + page_shift + order); if (err) return err; - addr += 1UL << page_shift; + addr += 1UL << (page_shift + order); + i += 1U << (order + page_shift - PAGE_SHIFT); } return 0; -- 2.39.3 (Apple Git-146)

3 months

[PATCH 0/5] New DRM accel driver for Texas Instruments' C7x DSPs

by Tomeu Vizoso

This series adds a new DRM/Accel driver that supports the C7x DSPs inside some Texas Instruments SoCs such as the J722S. These can be used as accelerators for various workloads, including machine learning inference. This driver controls the power state of the hardware via remoteproc and communicates with the firmware running on the DSP via rpmsg_virtio. The kernel driver itself allocates buffers, manages contexts, and submits jobs to the DSP firmware. Buffers are mapped by the DSP itself using its MMU, providing memory isolation among different clients. The source code for the firmware running on the DSP is available at: https://gitlab.freedesktop.org/tomeu/thames_firmware/. Everything else is done in userspace, as a Gallium driver (also called thames) that is part of the Mesa3D project: https://docs.mesa3d.org/teflon.html If there is more than one core that advertises the same rpmsg_virtio service name, the driver will load balance jobs between them with drm-gpu-scheduler. Userspace portion of the driver: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39298 Signed-off-by: Tomeu Vizoso <tomeu(a)tomeuvizoso.net> --- Tomeu Vizoso (5): arm64: dts: ti: k3-j722s-ti-ipc-firmware: Add memory pool for DSP i/o buffers accel/thames: Add driver for the C7x DSPs in TI SoCs accel/thames: Add IOCTLs for BO creation and mapping accel/thames: Add IOCTL for job submission accel/thames: Add IOCTL for memory synchronization Documentation/accel/thames/index.rst | 28 ++ MAINTAINERS | 9 + .../boot/dts/ti/k3-j722s-ti-ipc-firmware.dtsi | 11 +- drivers/accel/Kconfig | 1 + drivers/accel/Makefile | 3 +- drivers/accel/thames/Kconfig | 26 ++ drivers/accel/thames/Makefile | 11 + drivers/accel/thames/thames_core.c | 161 +++++++ drivers/accel/thames/thames_core.h | 53 +++ drivers/accel/thames/thames_device.c | 93 +++++ drivers/accel/thames/thames_device.h | 46 ++ drivers/accel/thames/thames_drv.c | 180 ++++++++ drivers/accel/thames/thames_drv.h | 21 + drivers/accel/thames/thames_gem.c | 407 ++++++++++++++++++ drivers/accel/thames/thames_gem.h | 45 ++ drivers/accel/thames/thames_ipc.h | 204 +++++++++ drivers/accel/thames/thames_job.c | 463 +++++++++++++++++++++ drivers/accel/thames/thames_job.h | 51 +++ drivers/accel/thames/thames_rpmsg.c | 276 ++++++++++++ drivers/accel/thames/thames_rpmsg.h | 27 ++ 20 files changed, 2113 insertions(+), 3 deletions(-) --- base-commit: 27927a79b3c6aebd18f38507a8160294243763dc change-id: 20260113-thames-334127a2d91d Best regards, -- Tomeu Vizoso <tomeu(a)tomeuvizoso.net>

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Linaro-mm-sig January 2026