Re: [PATCH] mm: Fix access_remote_vm() regression on tagged addresses

From: Linus Torvalds
Date: Wed Aug 09 2023 - 11:05:59 EST


On Wed, 9 Aug 2023 at 07:46, Kirill A. Shutemov
<kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
>
> mem_rw() of procfs uses access_remote_vm() to get data from the target
> process. It worked fine until recent changes in __access_remote_vm()
> that now checks if there's VMA at target address using raw address.
>
> Untag the address before looking up the VMA.

Interesting that it took this long to notice.

Not surprising considering that LAM isn't actually available, but I'd
have expected the arm people to notice more. Yes, I have (and test) my
arm64 laptop, but I obviously don't do user space debugging on it.
Apparently others don't either.

Or maybe TBI is used a lot less than I thought.

Anyway, obviously applied,

Linus