Re: [PATCH RFC 3/3] mm/vmalloc.c: allow vread() to read out vm_map_ram areas

[Matthew Wilcox]

On Wed, Nov 09, 2022 at 11:35:34AM +0800, Baoquan He wrote:
> Currently, vread() can read out vmalloc areas which is associated with
> a vm_struct. While this doesn't work for areas created by vm_map_ram()
> interface because it doesn't allocate a vm_struct. Then in vread(),
> these areas will be skipped.
> 
> Here, add a new function vb_vread() to read out areas managed by
> vmap_block specifically. Then recognize vm_map_ram areas via vmap->flags
> and handle  them respectively.

i don't understand how this deals with the original problem identified,
that the vread() can race with an unmap.