From: Alice Ryhl <aliceryhl@google.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Boqun Feng" <boqun@kernel.org>,
"Greg KH" <gregkh@linuxfoundation.org>,
"Andreas Hindborg" <a.hindborg@kernel.org>,
"Lorenzo Stoakes" <lorenzo.stoakes@oracle.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
"Miguel Ojeda" <ojeda@kernel.org>,
"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>,
"Will Deacon" <will@kernel.org>,
"Mark Rutland" <mark.rutland@arm.com>,
linux-mm@kvack.org, rust-for-linux@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] rust: page: add byte-wise atomic memory copy methods
Date: Tue, 17 Feb 2026 09:33:40 +0000 [thread overview]
Message-ID: <aZQ19FEeGgigdwz9@google.com> (raw)
In-Reply-To: <20260217091348.GT1395266@noisy.programming.kicks-ass.net>
On Tue, Feb 17, 2026 at 10:13:48AM +0100, Peter Zijlstra wrote:
> On Fri, Feb 13, 2026 at 08:19:17AM -0800, Boqun Feng wrote:
> > Well, in standard C, technically memcpy() has the same problem as Rust's
> > `core::ptr::copy()` and `core::ptr::copy_nonoverlapping()`, i.e. they
> > are vulnerable to data races. Our in-kernel memcpy() on the other hand
> > doesn't have this problem. Why? Because it's volatile byte-wise atomic
> > per the implementation.
>
> Look at arch/x86/lib/memcpy_64.S, plenty of movq variants there. Not
> byte-wise.
movq is a valid implementation of 8 byte-wise copies.
> Also, not a single atomic operation in sight.
Relaxed atomics are just mov ops.
Alice
next prev parent reply other threads:[~2026-02-17 9:33 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-12 14:51 Andreas Hindborg
2026-02-12 16:41 ` Boqun Feng
2026-02-12 17:10 ` Andreas Hindborg
2026-02-12 17:23 ` Andreas Hindborg
2026-02-13 9:55 ` Peter Zijlstra
2026-02-13 12:18 ` Greg KH
2026-02-13 12:58 ` Andreas Hindborg
2026-02-13 13:20 ` Greg KH
2026-02-13 14:13 ` Andreas Hindborg
2026-02-13 14:26 ` Peter Zijlstra
2026-02-13 15:34 ` Greg KH
2026-02-13 15:45 ` Boqun Feng
2026-02-13 15:58 ` Greg KH
2026-02-13 16:19 ` Boqun Feng
2026-02-17 9:13 ` Peter Zijlstra
2026-02-17 9:33 ` Alice Ryhl [this message]
2026-02-17 9:45 ` Peter Zijlstra
2026-02-17 10:01 ` Alice Ryhl
2026-02-17 10:25 ` Peter Zijlstra
2026-02-17 10:47 ` Alice Ryhl
2026-02-17 11:09 ` Peter Zijlstra
2026-02-17 11:51 ` Alice Ryhl
2026-02-17 12:09 ` Peter Zijlstra
2026-02-17 13:00 ` Peter Zijlstra
2026-02-17 13:54 ` Danilo Krummrich
2026-02-17 15:50 ` Peter Zijlstra
2026-02-17 16:10 ` Danilo Krummrich
2026-02-17 13:09 ` Alice Ryhl
2026-02-17 15:48 ` Peter Zijlstra
2026-02-17 23:39 ` Gary Guo
2026-02-18 8:37 ` Peter Zijlstra
2026-02-18 9:31 ` Alice Ryhl
2026-02-18 10:09 ` Peter Zijlstra
2026-02-17 13:56 ` Andreas Hindborg
2026-02-17 16:04 ` Peter Zijlstra
2026-02-17 18:43 ` Andreas Hindborg
2026-02-17 20:32 ` Jens Axboe
2026-02-17 15:52 ` Boqun Feng
2026-02-17 9:17 ` Peter Zijlstra
2026-02-17 9:23 ` Peter Zijlstra
2026-02-17 9:37 ` Alice Ryhl
2026-02-17 10:01 ` Peter Zijlstra
2026-02-17 9:33 ` Peter Zijlstra
2026-02-14 0:07 ` Gary Guo
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