# Re: \[PATCH 1/1\] fbdev: hyperv\_fb: iounmap() the correct memory when removing a device

- From: Wei Liu \<wei.liu@kernel.org\>
- Date: 2025-02-12 02:27:29 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2025/02/2922728
- Thread: https://ratatoskr.run/dri-devel/2025/02/2918549/t.md

```text
On Sun, Feb 09, 2025 at 03:52:52PM -0800, mhkelley58@gmail.com wrote:
> From: Michael Kelley <redacted>
> 
> When a Hyper-V framebuffer device is removed, or the driver is unbound
> from a device, any allocated and/or mapped memory must be released. In
> particular, MMIO address space that was mapped to the framebuffer must
> be unmapped. Current code unmaps the wrong address, resulting in an
> error like:
> 
> [ 4093.980597] iounmap: bad address 00000000c936c05c
> 
> followed by a stack dump.
> 
> Commit d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for
> Hyper-V frame buffer driver") changed the kind of address stored in
> info->screen_base, and the iounmap() call in hvfb_putmem() was not
> updated accordingly.
> 
> Fix this by updating hvfb_putmem() to unmap the correct address.
> 
> Fixes: d21987d709e8 ("video: hyperv: hyperv_fb: Support deferred IO for Hyper-V frame buffer driver")
> Signed-off-by: Michael Kelley <redacted>

Applied to hyperv-fixes. Thanks.
```