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Wed, 18 Feb 2026 03:57:10 -0800 (PST) MIME-Version: 1.0 References: <20260213-page-volatile-io-v3-1-d60487b04d40@kernel.org> In-Reply-To: <20260213-page-volatile-io-v3-1-d60487b04d40@kernel.org> From: Miguel Ojeda Date: Wed, 18 Feb 2026 12:56:58 +0100 X-Gm-Features: AaiRm50hToXgBrb4YdoI6g2TqLtBaS1_xidHsii392EXlW0MJCp-m0oWjTwIcQ4 Message-ID: Subject: Re: [PATCH v3] rust: page: add byte-wise atomic memory copy methods To: Andreas Hindborg , Benno Lossin Cc: Alice Ryhl , Lorenzo Stoakes , "Liam R. Howlett" , Miguel Ojeda , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Trevor Gross , Danilo Krummrich , Will Deacon , Peter Zijlstra , Mark Rutland , linux-mm@kvack.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 5tjxebs9jczott99fwrwa5htruwn46bh X-Rspam-User: X-Rspamd-Queue-Id: 457BFA000B X-Rspamd-Server: rspam01 X-HE-Tag: 1771415832-457005 X-HE-Meta: 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 7FpyCOKF 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Feb 13, 2026 at 7:43=E2=80=AFAM Andreas Hindborg wrote: > > @@ -282,6 +318,7 @@ pub unsafe fn read_raw(&self, dst: *mut u8, offset: u= size, len: usize) -> Result > /// # Safety > /// > /// * Callers must ensure that `src` is valid for reading `len` byte= s. > + /// * Callers must ensure that there are no concurrent writes to the= source memory region. > /// * Callers must ensure that this call does not race with a read o= r write to the same page > /// that overlaps with this write. > pub unsafe fn write_raw(&self, src: *const u8, offset: usize, len: u= size) -> Result { Coming from: https://lore.kernel.org/rust-for-linux/20260215-page-additions-v1-0-48277= 90a9bc4@kernel.org/T/#md120cdea73132fc698bf69bf3d69287c2cb28449 Leaving a comment here to avoid forgetting: I think the new bullet point here and elsewhere is not needed, i.e. the first one uses "valid for reads" which I think is meant to already exclude data races. > + /// - For the duration of the call, other accesses to the areas desc= ribed by `src` and `len`, > + /// must not cause data races (defined by [`LKMM`]) against atomic= operations executed by this > + /// function. Note that if all other accesses are atomic, then thi= s safety requirement is > + /// trivially fulfilled. And, for this one, Benno said perhaps we should introduce a shorthand. Cheers, Miguel