Re: [PATCH v5 1/2] mm/process_vm_access: pidfd and nowait support for process_vm_readv/writev

[Christian Brauner]

On 2026-06-03 15:54 +0200, David Hildenbrand (Arm) wrote:
> > However, the exited-leader case is a real limitation for profilers.
> > OpenTelemetry eBPF Profiler wants to profile a process where the main thread
> > has exited but secondary threads are still running [2].
> > [2] https://github.com/open-telemetry/opentelemetry-ebpf-profiler/pull/376
> > 
> > Using plain TIDs (flags=0) would work, but it means users cannot use
> > PROCESS_VM_PIDFD in this scenario.
> > 
> > What do you think this patch should do? I see two options:
> >  - Address this limitation in a separate future patch that fixes
> >    pidfd_get_task() to use PIDTYPE_PID when PIDFD_THREAD is detected in
> >    f_flags, benefiting all callers (process_vm_readv, process_madvise,
> >    and any future users).
> 
> Extending it consistently for that scenario seems like the right thing to do?
> @Christian?

Yes, but I cannot vouch whether the mm operations deal correctively with
subthreads.