Re: [RFC PATCH 27/39] KVM: guest_memfd: Allow mmapping guest_memfd files

[Peter Xu]

On Tue, Sep 10, 2024 at 11:43:58PM +0000, Ackerley Tng wrote:
> @@ -790,6 +791,9 @@ static long kvm_gmem_punch_hole(struct inode *inode, loff_t offset, loff_t len)
>  	 */
>  	filemap_invalidate_lock(inode->i_mapping);
>  
> +	/* TODO: Check if even_cows should be 0 or 1 */
> +	unmap_mapping_range(inode->i_mapping, start, len, 0);

Should be s/start/offset/ here, or should expect some filemap crash assert
on non-zero mapcounts (when it starts to matter).

Btw, it would be nice if the new version would allow kvm to be compiled as
a module.  Currently it uses a lot of mm functions that are not yet
exported, so AFAIU it will only build if kvm is builtin.

Thanks,

-- 
Peter Xu