Claude review: media: videobuf2: Set vma_flags in vb2_dma_sg_mmap

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Overall Series Review

Subject: media: videobuf2: Set vma_flags in vb2_dma_sg_mmap
Author: Janne Grunau <j@jannau.net>
Patches: 1
Reviewed: 2026-02-16T06:42:02.240640

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This is a single-patch series that adds `VM_DONTEXPAND | VM_DONTDUMP` flags to the `vb2_dma_sg_mmap()` function in the videobuf2 DMA scatter/gather allocator. The `vb2_dma_contig` allocator already sets these flags in its mmap handler, and the vmalloc allocator sets `VM_DONTEXPAND`. The missing flags cause a `WARN_ON` in `drm_gem_mmap_obj()` when a DRM driver imports a dma-buf from a V4L2 device that uses `vb2_dma_sg_memops` and the buffer is subsequently mmapped through the DRM GEM path.

The fix is straightforward, correct, and consistent with the existing pattern in the sibling allocators. The commit message is thorough — it explains the problem, provides the call trace, references prior discussion about the broader question of mmap on imported dma-bufs, and includes appropriate Fixes and Cc: stable tags.

No issues found.

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