On 12/2/24 20:19, Jocelyn Falempe wrote:

quoted

quoted

I've now noticed that drm_gem_shmem_vmap() expects BO reservation lock
to be held and we can't take lock it at a panic time.

https://elixir.bootlin.com/linux/v6.12.1/source/drivers/gpu/drm/
drm_gem_shmem_helper.c#L330

This resv warning isn't triggered because bo->base.vaddr is set for VT
framebufffer BO when panic happens.

I usually test using gnome desktop in the VM, and in this case vaddr is
not set, and calling vmap() is needed. (and I don't get the warning, I
will check why).

All those get_pages() and vmap() that drm_gem_shmem_vmap() uses may
sleep. You'll need to add atomic variants for the vmap funcs if it's
really needed.

Like I said in the comment to v6, let's start with rejecting BOs that
aren't vmapped. If atomic vmap will become needed, it will be a separate
problem to solve.

-- 
Best regards,
Dmitry