Linaro-mm-sig December 2025

linaro-mm-sig@lists.linaro.org

56 participants
42 discussions

[PATCH] dma-buf: fix WARNING in dma_buf_vmap

by Szymon Wilczek

When a driver's vmap callback returns an error (e.g. -ENOMEM), dma_buf_vmap() triggers a WARN_ON_ONCE(). This is incorrect as vmap operations can legitimately fail due to resource exhaustion or other transient conditions, as documented. Fix this by removing the WARN_ON_ONCE(). The error code is already correctly propagated to the caller. Reported-by: syzbot+cd944c467e4d4bc24cf6(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug\?extid\=4317d7108e14e5d56308 Signed-off-by: Szymon Wilczek <szymonwilczek(a)gmx.com> --- drivers/dma-buf/dma-buf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index edaa9e4ee4ae..14b55f67ee1c 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1525,7 +1525,7 @@ int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map) BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr)); ret = dmabuf->ops->vmap(dmabuf, &ptr); - if (WARN_ON_ONCE(ret)) + if (ret) return ret; dmabuf->vmap_ptr = ptr; -- 2.52.0

3 months, 4 weeks

[PATCH 0/4] Rust GPUVM support

by Alice Ryhl

This makes a few changes to the way immediate mode works, and then it implements a Rust immediate mode GPUVM abstraction on top of that. Please see the following branch for example usage in Tyr: https://gitlab.freedesktop.org/panfrost/linux/-/merge_requests/53 For context, please see this previous patch: https://lore.kernel.org/rust-for-linux/20250621-gpuvm-v3-1-10203da06867@col… and the commit message of the last patch. Signed-off-by: Alice Ryhl <aliceryhl(a)google.com> --- Alice Ryhl (4): drm/gpuvm: take GEM lock inside drm_gpuvm_bo_obtain_prealloc() drm/gpuvm: drm_gpuvm_bo_obtain() requires lock and staged mode drm/gpuvm: use const for drm_gpuva_op_* ptrs rust: drm: add GPUVM immediate mode abstraction MAINTAINERS | 1 + drivers/gpu/drm/drm_gpuvm.c | 80 ++++-- drivers/gpu/drm/imagination/pvr_vm.c | 2 +- drivers/gpu/drm/msm/msm_gem.h | 2 +- drivers/gpu/drm/msm/msm_gem_vma.c | 2 +- drivers/gpu/drm/nouveau/nouveau_uvmm.c | 2 +- drivers/gpu/drm/panthor/panthor_mmu.c | 10 - drivers/gpu/drm/xe/xe_vm.c | 4 +- include/drm/drm_gpuvm.h | 12 +- rust/bindings/bindings_helper.h | 2 + rust/helpers/drm_gpuvm.c | 43 +++ rust/helpers/helpers.c | 1 + rust/kernel/drm/gpuvm/mod.rs | 394 +++++++++++++++++++++++++++ rust/kernel/drm/gpuvm/sm_ops.rs | 469 +++++++++++++++++++++++++++++++++ rust/kernel/drm/gpuvm/va.rs | 148 +++++++++++ rust/kernel/drm/gpuvm/vm_bo.rs | 213 +++++++++++++++ rust/kernel/drm/mod.rs | 1 + 17 files changed, 1337 insertions(+), 49 deletions(-) --- base-commit: 77b686f688126a5f758b51441a03186e9eb1b0f1 change-id: 20251128-gpuvm-rust-b719cac27ad6 Best regards, -- Alice Ryhl <aliceryhl(a)google.com>

3 months, 4 weeks

Re: [PATCH 2/4] drm/gpuvm: drm_gpuvm_bo_obtain() requires lock and staged mode

by dakr＠kernel.org

The content of this message was lost. It was probably cross-posted to multiple lists and previously handled on another list.

4 months

[PATCH mm-hotfixes 0/4] mm kernel-doc fixes

by Bagas Sanjaya

Hi, Here are kernel-doc fixes for mm subsystem, based on mm-hotfixes-unstable branch. This series is split from previous assorted kernel-doc fixes series [1] with review trailers applied. I'm also including textsearch fix since there's currently no maintainer for include/linux/textsearch.h (get_maintainer.pl only shows LKML). Enjoy! [1]: https://lore.kernel.org/linux-fsdevel/20251215113903.46555-1-bagasdotme@gma… Bagas Sanjaya (4): mm: Describe @flags parameter in memalloc_flags_save() textsearch: Describe @list member in ts_ops search mm: vmalloc: Fix up vrealloc_node_align() kernel-doc macro name mm, kfence: Describe @slab parameter in __kfence_obj_info() include/linux/kfence.h | 1 + include/linux/sched/mm.h | 1 + include/linux/textsearch.h | 1 + mm/vmalloc.c | 2 +- 4 files changed, 4 insertions(+), 1 deletion(-) base-commit: 980dbceadd50af9437257d8095d4a3606818e8c4 -- An old man doll... just what I always wanted! - Clara

4 months

[PATCH 00/12] media: stm32: dcmi: stability & performance enhancements

by Alain Volmat

This series improve stability of the capture by fixing the handling of the overrun which was leading to captured frame corruption. Locking within the driver is also simplified and the way DMA is handled is reworked allowing to avoid having a specific handling for the JPEG data. Performances of capture can now be increased via the usage of a DMA->MDMA chaining which allows for capture of higher resolution / framerate. Signed-off-by: Alain Volmat <alain.volmat(a)foss.st.com> --- Alain Volmat (12): media: stm32: dcmi: Switch from __maybe_unused to pm_sleep_ptr() media: stm32: dcmi: perform dmaengine_slave_config at probe media: stm32: dcmi: only create dma descriptor once at buf_prepare media: stm32: dcmi: stop the dma transfer on overrun media: stm32: dcmi: rework spin_lock calls media: stm32: dcmi: perform all dma handling within irq_thread media: stm32: dcmi: use dmaengine_terminate_async in irq context media: stm32: dcmi: continuous mode capture in JPEG dt-bindings: media: st: dcmi: add DMA-MDMA chaining properties media: stm32: dcmi: addition of DMA-MDMA chaining support ARM: dts: stm32: add sram node within stm32mp151.dtsi ARM: dts: stm32: enable DCMI DMA-MDMA chaining on stm32mp157c-ev1.dts .../devicetree/bindings/media/st,stm32-dcmi.yaml | 13 +- arch/arm/boot/dts/st/stm32mp151.dtsi | 8 + arch/arm/boot/dts/st/stm32mp157c-ev1.dts | 15 + drivers/media/platform/st/stm32/stm32-dcmi.c | 470 ++++++++++++++------- 4 files changed, 341 insertions(+), 165 deletions(-) --- base-commit: f7231cff1f3ff8259bef02dc4999bc132abf29cf change-id: 20251213-stm32-dcmi-dma-chaining-9ea1da83007d Best regards, -- Alain Volmat <alain.volmat(a)foss.st.com>

4 months

[PATCH] drm/imagination: Disallow exporting of PM/FW protected objects

by Alessio Belle

These objects are meant to be used by the GPU firmware or by the PM unit within the GPU, in which case they may contain physical addresses. This adds a layer of protection against exposing potentially exploitable information outside of the driver. Fixes: ff5f643de0bf ("drm/imagination: Add GEM and VM related code") Signed-off-by: Alessio Belle <alessio.belle(a)imgtec.com> --- drivers/gpu/drm/imagination/pvr_gem.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/imagination/pvr_gem.c b/drivers/gpu/drm/imagination/pvr_gem.c index a66cf082af24..c07c9a915190 100644 --- a/drivers/gpu/drm/imagination/pvr_gem.c +++ b/drivers/gpu/drm/imagination/pvr_gem.c @@ -28,6 +28,16 @@ static void pvr_gem_object_free(struct drm_gem_object *obj) drm_gem_shmem_object_free(obj); } +static struct dma_buf *pvr_gem_export(struct drm_gem_object *obj, int flags) +{ + struct pvr_gem_object *pvr_obj = gem_to_pvr_gem(obj); + + if (pvr_obj->flags & DRM_PVR_BO_PM_FW_PROTECT) + return ERR_PTR(-EPERM); + + return drm_gem_prime_export(obj, flags); +} + static int pvr_gem_mmap(struct drm_gem_object *gem_obj, struct vm_area_struct *vma) { struct pvr_gem_object *pvr_obj = gem_to_pvr_gem(gem_obj); @@ -42,6 +52,7 @@ static int pvr_gem_mmap(struct drm_gem_object *gem_obj, struct vm_area_struct *v static const struct drm_gem_object_funcs pvr_gem_object_funcs = { .free = pvr_gem_object_free, .print_info = drm_gem_shmem_object_print_info, + .export = pvr_gem_export, .pin = drm_gem_shmem_object_pin, .unpin = drm_gem_shmem_object_unpin, .get_sg_table = drm_gem_shmem_object_get_sg_table, --- base-commit: ca2583412306ceda9304a7c4302fd9efbf43e963 change-id: 20251128-no-export-pm-fw-obj-aeca634ddd0a Best regards, -- Alessio Belle <alessio.belle(a)imgtec.com>

4 months

Re: [PATCH 05/19] dma-buf/selftests: test RCU ops and inline lock

by tursulin＠ursulin.net

The content of this message was lost. It was probably cross-posted to multiple lists and previously handled on another list.

4 months

[PATCH 00/14] Assorted kernel-doc fixes

by Bagas Sanjaya

Hi, Here are assorted kernel-doc fixes for 6.19 cycle. As the name implies, for the merging strategy, the patches can be taken by respective maintainers to appropriate fixes branches (targetting 6.19 of course) (e.g. for mm it will be mm-hotfixes). Enjoy! Bagas Sanjaya (14): genalloc: Describe @start_addr parameter in genpool_algo_t mm: Describe @flags parameter in memalloc_flags_save() textsearch: Describe @list member in ts_ops search mm: vmalloc: Fix up vrealloc_node_align() kernel-doc macro name mm, kfence: Describe @slab parameter in __kfence_obj_info() virtio: Describe @map and @vmap members in virtio_device struct fs: Describe @isnew parameter in ilookup5_nowait() VFS: fix __start_dirop() kernel-doc warnings drm/amd/display: Don't use kernel-doc comment in dc_register_software_state struct drm/amdgpu: Describe @AMD_IP_BLOCK_TYPE_RAS in amd_ip_block_type enum drm/gem/shmem: Describe @shmem and @size parameters drm/scheduler: Describe @result in drm_sched_job_done() drm/gpusvm: Fix drm_gpusvm_pages_valid_unlocked() kernel-doc comment net: bridge: Describe @tunnel_hash member in net_bridge_vlan_group struct drivers/gpu/drm/amd/display/dc/dc.h | 2 +- drivers/gpu/drm/amd/include/amd_shared.h | 1 + drivers/gpu/drm/drm_gem_shmem_helper.c | 3 ++- drivers/gpu/drm/drm_gpusvm.c | 4 ++-- drivers/gpu/drm/scheduler/sched_main.c | 1 + fs/inode.c | 1 + fs/namei.c | 3 ++- include/linux/genalloc.h | 1 + include/linux/kfence.h | 1 + include/linux/sched/mm.h | 1 + include/linux/textsearch.h | 1 + include/linux/virtio.h | 2 ++ mm/vmalloc.c | 2 +- net/bridge/br_private.h | 1 + 14 files changed, 18 insertions(+), 6 deletions(-) base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8 -- An old man doll... just what I always wanted! - Clara

4 months

[PATCH v6 00/11] vfio/pci: Allow MMIO regions to be exported through dma-buf

by Leon Romanovsky

Changelog: v6: * Fixed wrong error check from pcim_p2pdma_init(). * Documented pcim_p2pdma_provider() function. * Improved commit messages. * Added VFIO DMA-BUF selftest. * Added __counted_by(nr_ranges) annotation to struct vfio_device_feature_dma_buf. * Fixed error unwind when dma_buf_fd() fails. * Document latest changes to p2pmem. * Removed EXPORT_SYMBOL_GPL from pci_p2pdma_map_type. * Moved DMA mapping logic to DMA-BUF. * Removed types patch to avoid dependencies between subsystems. * Moved vfio_pci_dma_buf_move() in err_undo block. * Added nvgrace patch. v5: https://lore.kernel.org/all/cover.1760368250.git.leon@kernel.org * Rebased on top of v6.18-rc1. * Added more validation logic to make sure that DMA-BUF length doesn't overflow in various scenarios. * Hide kernel config from the users. * Fixed type conversion issue. DMA ranges are exposed with u64 length, but DMA-BUF uses "unsigned int" as a length for SG entries. * Added check to prevent from VFIO drivers which reports BAR size different from PCI, do not use DMA-BUF functionality. v4: https://lore.kernel.org/all/cover.1759070796.git.leon@kernel.org * Split pcim_p2pdma_provider() to two functions, one that initializes array of providers and another to return right provider pointer. v3: https://lore.kernel.org/all/cover.1758804980.git.leon@kernel.org * Changed pcim_p2pdma_enable() to be pcim_p2pdma_provider(). * Cache provider in vfio_pci_dma_buf struct instead of BAR index. * Removed misleading comment from pcim_p2pdma_provider(). * Moved MMIO check to be in pcim_p2pdma_provider(). v2: https://lore.kernel.org/all/cover.1757589589.git.leon@kernel.org/ * Added extra patch which adds new CONFIG, so next patches can reuse * it. * Squashed "PCI/P2PDMA: Remove redundant bus_offset from map state" into the other patch. * Fixed revoke calls to be aligned with true->false semantics. * Extended p2pdma_providers to be per-BAR and not global to whole * device. * Fixed possible race between dmabuf states and revoke. * Moved revoke to PCI BAR zap block. v1: https://lore.kernel.org/all/cover.1754311439.git.leon@kernel.org * Changed commit messages. * Reused DMA_ATTR_MMIO attribute. * Returned support for multiple DMA ranges per-dMABUF. v0: https://lore.kernel.org/all/cover.1753274085.git.leonro@nvidia.com --------------------------------------------------------------------------- Based on "[PATCH v6 00/16] dma-mapping: migrate to physical address-based API" https://lore.kernel.org/all/cover.1757423202.git.leonro@nvidia.com/ series. --------------------------------------------------------------------------- This series extends the VFIO PCI subsystem to support exporting MMIO regions from PCI device BARs as dma-buf objects, enabling safe sharing of non-struct page memory with controlled lifetime management. This allows RDMA and other subsystems to import dma-buf FDs and build them into memory regions for PCI P2P operations. The series supports a use case for SPDK where a NVMe device will be owned by SPDK through VFIO but interacting with a RDMA device. The RDMA device may directly access the NVMe CMB or directly manipulate the NVMe device's doorbell using PCI P2P. However, as a general mechanism, it can support many other scenarios with VFIO. This dmabuf approach can be usable by iommufd as well for generic and safe P2P mappings. In addition to the SPDK use-case mentioned above, the capability added in this patch series can also be useful when a buffer (located in device memory such as VRAM) needs to be shared between any two dGPU devices or instances (assuming one of them is bound to VFIO PCI) as long as they are P2P DMA compatible. The implementation provides a revocable attachment mechanism using dma-buf move operations. MMIO regions are normally pinned as BARs don't change physical addresses, but access is revoked when the VFIO device is closed or a PCI reset is issued. This ensures kernel self-defense against potentially hostile userspace. The series includes significant refactoring of the PCI P2PDMA subsystem to separate core P2P functionality from memory allocation features, making it more modular and suitable for VFIO use cases that don't need struct page support. ----------------------------------------------------------------------- The series is based originally on https://lore.kernel.org/all/20250307052248.405803-1-vivek.kasireddy@intel.c… but heavily rewritten to be based on DMA physical API. ----------------------------------------------------------------------- The WIP branch can be found here: https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?h=… Thanks --- Jason Gunthorpe (2): PCI/P2PDMA: Document DMABUF model vfio/nvgrace: Support get_dmabuf_phys Leon Romanovsky (7): PCI/P2PDMA: Separate the mmap() support from the core logic PCI/P2PDMA: Simplify bus address mapping API PCI/P2PDMA: Refactor to separate core P2P functionality from memory allocation PCI/P2PDMA: Provide an access to pci_p2pdma_map_type() function dma-buf: provide phys_vec to scatter-gather mapping routine vfio/pci: Enable peer-to-peer DMA transactions by default vfio/pci: Add dma-buf export support for MMIO regions Vivek Kasireddy (2): vfio: Export vfio device get and put registration helpers vfio/pci: Share the core device pointer while invoking feature functions Documentation/driver-api/pci/p2pdma.rst | 95 +++++++--- block/blk-mq-dma.c | 2 +- drivers/dma-buf/dma-buf.c | 235 ++++++++++++++++++++++++ drivers/iommu/dma-iommu.c | 4 +- drivers/pci/p2pdma.c | 182 +++++++++++++----- drivers/vfio/pci/Kconfig | 3 + drivers/vfio/pci/Makefile | 1 + drivers/vfio/pci/nvgrace-gpu/main.c | 56 ++++++ drivers/vfio/pci/vfio_pci.c | 5 + drivers/vfio/pci/vfio_pci_config.c | 22 ++- drivers/vfio/pci/vfio_pci_core.c | 56 ++++-- drivers/vfio/pci/vfio_pci_dmabuf.c | 315 ++++++++++++++++++++++++++++++++ drivers/vfio/pci/vfio_pci_priv.h | 23 +++ drivers/vfio/vfio_main.c | 2 + include/linux/dma-buf.h | 18 ++ include/linux/pci-p2pdma.h | 120 +++++++----- include/linux/vfio.h | 2 + include/linux/vfio_pci_core.h | 42 +++++ include/uapi/linux/vfio.h | 27 +++ kernel/dma/direct.c | 4 +- mm/hmm.c | 2 +- 21 files changed, 1077 insertions(+), 139 deletions(-) --- base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787 change-id: 20251016-dmabuf-vfio-6cef732adf5a Best regards, -- Leon Romanovsky <leonro(a)nvidia.com>

4 months

[PATCH] dma-buf: really enable DMABUF_DEBUG by default on DEBUG kernels

by Lukas Bulwahn

From: Lukas Bulwahn <lukas.bulwahn(a)redhat.com> The intent of commit 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels") is clear, but it mixes up the config option name. The config option for kernel debugging is named DEBUG_KERNEL, not DEBUG. Fix up the DMABUF_DEBUG definition to use the intended name. Fixes: 646013f513f3 ("dma-buf: enable DMABUF_DEBUG by default on DEBUG kernels") Signed-off-by: Lukas Bulwahn <lukas.bulwahn(a)redhat.com> --- drivers/dma-buf/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig index fdd823e446cc..426c9ad3364f 100644 --- a/drivers/dma-buf/Kconfig +++ b/drivers/dma-buf/Kconfig @@ -55,7 +55,7 @@ config DMABUF_MOVE_NOTIFY config DMABUF_DEBUG bool "DMA-BUF debug checks" depends on DMA_SHARED_BUFFER - default y if DEBUG + default y if DEBUG_KERNEL help This option enables additional checks for DMA-BUF importers and exporters. Specifically it validates that importers do not peek at the -- 2.51.1

4 months

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Linaro-mm-sig December 2025