Re: [PATCHv16 05/17] mm: Introduce untagged_addr_remote()

[Edgecombe, Rick P]

On Sun, 2023-03-12 at 14:26 +0300, Kirill A. Shutemov wrote:
> untagged_addr() removes tags/metadata from the address and brings it
> to
> the canonical form. The helper is implemented on arm64 and sparc.
> Both of
> them do untagging based on global rules.
> 
> However, Linear Address Masking (LAM) on x86 introduces per-process
> settings for untagging. As a result, untagged_addr() is now only
> suitable for untagging addresses for the current proccess.
> 
> The new helper untagged_addr_remote() has to be used when the address
> targets remote process. It requires the mmap lock for target mm to be
> taken.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Tested-by: Alexander Potapenko <glider@xxxxxxxxxx>

Seems to cover all the untagged_addr() cases that were operating on a
non-current MM.

Reviewed-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>