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From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
To: Alice Ryhl <aliceryhl@google.com>
Cc: "Tamir Duberstein" <tamird@kernel.org>,
	"Andreas Hindborg" <a.hindborg@kernel.org>,
	"Tamir Duberstein" <tamird@gmail.com>,
	"Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Benno Lossin" <lossin@kernel.org>,
	"Trevor Gross" <tmgross@umich.edu>,
	"Danilo Krummrich" <dakr@kernel.org>,
	"Lorenzo Stoakes" <lorenzo.stoakes@oracle.com>,
	"Vlastimil Babka" <vbabka@suse.cz>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Christoph Lameter" <cl@gentwo.org>,
	"David Rientjes" <rientjes@google.com>,
	"Roman Gushchin" <roman.gushchin@linux.dev>,
	"Harry Yoo" <harry.yoo@oracle.com>,
	"Daniel Gomez" <da.gomez@kernel.org>,
	rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH v3 05/12] rust: xarray: use `xas_load` instead of `xa_load` in `Guard::load`
Date: Wed, 11 Feb 2026 09:32:36 -0500	[thread overview]
Message-ID: <hq46fcdy6zvwcwlbtbjynqadiwy3wjs7raxioime2et5amzez6@wvzzlkiijwvf> (raw)
In-Reply-To: <CAH5fLghKwNEdVeRi3H3LQ9NTPYprpAeY41-jgfq8YEST9PaGdw@mail.gmail.com>

* Alice Ryhl <aliceryhl@google.com> [260210 16:34]:
> On Tue, Feb 10, 2026 at 10:23 PM Tamir Duberstein <tamird@kernel.org> wrote:
> >
> > On Tue, Feb 10, 2026 at 12:59 PM Liam R. Howlett
> > <Liam.Howlett@oracle.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/
> 

It would probably be worth having two loads then, one that does
rcu_read_lock()/unlock() and one for writer/advanced users like we have
on the C side of things.

Or at least name the load() function to indicate which is implemented
today?

At least on the maple tree side, we have both interfaces and users for
both.  I just found the change to remove the rcu safety odd because I
assumed both are needed.

Thanks,
Liam


  reply	other threads:[~2026-02-11 14:33 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-02-09 14:38 [PATCH v3 00/12] rust: xarray: add entry API with preloading Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 01/12] rust: xarray: minor formatting fixes Andreas Hindborg
2026-02-10 16:44   ` Daniel Gomez
2026-02-10 17:44   ` Liam R. Howlett
2026-02-11 18:30   ` Mukesh Kumar Chaurasiya
2026-02-09 14:38 ` [PATCH v3 02/12] rust: xarray: add debug format for `StoreError` Andreas Hindborg
2026-02-10 16:45   ` Daniel Gomez
2026-02-10 16:55     ` Tamir Duberstein
2026-02-10 17:44   ` Liam R. Howlett
2026-02-09 14:38 ` [PATCH v3 03/12] rust: xarray: add `contains_index` method Andreas Hindborg
2026-02-10 16:46   ` Daniel Gomez
2026-02-10 16:56   ` Tamir Duberstein
2026-02-11  7:31     ` Andreas Hindborg
2026-02-11 18:24       ` Tamir Duberstein
2026-02-10 17:52   ` Liam R. Howlett
2026-02-11  7:41     ` Andreas Hindborg
2026-02-11 18:21       ` Liam R. Howlett
2026-02-12 10:15         ` Andreas Hindborg
2026-02-12 10:52           ` Andreas Hindborg
2026-02-12 11:19             ` Alice Ryhl
2026-02-12 12:39               ` Andreas Hindborg
2026-02-12 17:49                 ` Liam R. Howlett
2026-02-13  8:15                   ` Alice Ryhl
2026-02-13  8:17                 ` Alice Ryhl
2026-02-12 11:27             ` Miguel Ojeda
2026-02-12 12:47               ` Andreas Hindborg
2026-02-12 13:34                 ` Miguel Ojeda
2026-02-09 14:38 ` [PATCH v3 04/12] rust: xarray: add `XArrayState` Andreas Hindborg
2026-02-10 16:48   ` Daniel Gomez
2026-02-11  7:42     ` Andreas Hindborg
2026-02-10 16:57   ` Tamir Duberstein
2026-02-09 14:38 ` [PATCH v3 05/12] rust: xarray: use `xas_load` instead of `xa_load` in `Guard::load` Andreas Hindborg
2026-02-10 18:16   ` Liam R. Howlett
2026-02-10 19:53     ` Tamir Duberstein
2026-02-10 20:59       ` Liam R. Howlett
2026-02-10 21:22         ` Tamir Duberstein
2026-02-10 21:34           ` Alice Ryhl
2026-02-11 14:32             ` Liam R. Howlett [this message]
2026-02-11 18:00               ` Boqun Feng
2026-02-11 18:19                 ` Tamir Duberstein
2026-02-11 18:24                   ` Boqun Feng
2026-02-11 18:55                 ` Liam R. Howlett
2026-02-11 19:45                   ` Boqun Feng
2026-02-09 14:38 ` [PATCH v3 06/12] rust: xarray: simplify `Guard::load` Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 07/12] rust: xarray: add `find_next` and `find_next_mut` Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 08/12] rust: xarray: add entry API Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 09/12] rust: mm: add abstractions for allocating from a `sheaf` Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 10/12] rust: mm: sheaf: allow use of C initialized static caches Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 11/12] xarray, radix-tree: enable sheaf support for kmem_cache Andreas Hindborg
2026-02-10 16:49   ` Daniel Gomez
2026-02-11  7:45     ` Andreas Hindborg
2026-02-09 14:38 ` [PATCH v3 12/12] rust: xarray: add preload API Andreas Hindborg

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