linux-kernel - Re: [PATCH v3 05/12] rust: xarray: use `xas_load` instead of `xa

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Message-ID: <CAH5fLghKwNEdVeRi3H3LQ9NTPYprpAeY41-jgfq8YEST9PaGdw@mail.gmail.com>
Date: Tue, 10 Feb 2026 22:34:04 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: Tamir Duberstein <tamird@...nel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@...cle.com>, Andreas Hindborg <a.hindborg@...nel.org>, 
	Tamir Duberstein <tamird@...il.com>, Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
	Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
	Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
	Benno Lossin <lossin@...nel.org>, Trevor Gross <tmgross@...ch.edu>, 
	Danilo Krummrich <dakr@...nel.org>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	Vlastimil Babka <vbabka@...e.cz>, Andrew Morton <akpm@...ux-foundation.org>, 
	Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>, 
	Roman Gushchin <roman.gushchin@...ux.dev>, Harry Yoo <harry.yoo@...cle.com>, 
	Daniel Gomez <da.gomez@...nel.org>, rust-for-linux@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v3 05/12] rust: xarray: use `xas_load` instead of
 `xa_load` in `Guard::load`

On Tue, Feb 10, 2026 at 10:23 PM Tamir Duberstein <tamird@...nel.org> wrote:
>
> On Tue, Feb 10, 2026 at 12:59 PM Liam R. Howlett
> <Liam.Howlett@...cle.com> wrote:
> > Is this a temporary limitation?
>
> Maybe? I don't think RfL has good abstractions for RCU yet. For
> example, exposing load directly on the xarray using xa_load would
> require a way to guarantee that the returned pointer's target isn't
> being concurrently mutated (e.g. under the xarray lock). I'm not aware
> of anyone asking for this, though.

It's relatively easy to add an rcu-backed load using the RCU
abstractions we have today. I already shared an RFC containing such a
method for the maple tree, and it would not be much different for
xarray.
https://lore.kernel.org/all/20260116-rcu-box-v1-0-38ebfbcd53f0@google.com/

Alice