Re: [PATCH] mm/vmalloc: fix mischeck pfn valid in vmap_pfns

[Huan Yang]

HI Christoph

Sorry for the later reply.

在 2025/3/20 13:31, Christoph Hellwig 写道:
> As mentioned before udmabuf also has a grave bug in the dma mapping
> part, so just marking it broken would be another very sensible

Could you please provide a more detailed description of this?

I'm not the maintainer, but I see the udmabuf's begin patch mentioned as:

A driver to let userspace turn memfd regions into dma-bufs.

Use case:  Allows qemu create dmabufs for the vga framebuffer or
virtio-gpu ressources.  Then they can be passed around to display
those guest things on the host.  To spice client for classic full
framebuffer display, and hopefully some day to wayland server for
seamless guest window display.

https://patchwork.freedesktop.org/patch/246100/

Did it also mean to do it?

I'd like to learn your thinking

Thank you,

Huan Yang

> option.