Re: [PATCH 0/2] uprobes,mm: speculative lockless VMA-to-uprobe lookup

[Jann Horn]

On Fri, Sep 6, 2024 at 7:12 AM Andrii Nakryiko <andrii@xxxxxxxxxx> wrote:
> Implement speculative (lockless) resolution of VMA to inode to uprobe,
> bypassing the need to take mmap_lock for reads, if possible. Patch #1 by Suren
> adds mm_struct helpers that help detect whether mm_struct were changed, which
> is used by uprobe logic to validate that speculative results can be trusted
> after all the lookup logic results in a valid uprobe instance.

Random thought: It would be nice if you could skip the MM stuff
entirely and instead go through the GUP-fast path, but I guess going
from a uprobe-created anon page to the corresponding uprobe is hard...
but maybe if you used the anon_vma pointer as a lookup key to find the
uprobe, it could work? Though then you'd need hooks in the anon_vma
code... maybe not such a great idea.