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AJvYcCWhScpwwTcez35mmR9BOFSrBsm3Ab/ZmexTAZAgSt4smZV+aIkAOo5GSkw3cLYovriT2bzmyZ94yA==@kvack.org X-Gm-Message-State: AOJu0YwWSL+BBFzL5FRWtGsjuzntBW0DnoiW6DsbosYWJJeFGHHzKGoN JJH79UiY/K/0GWnoiUPZXNF08NW8coaqqcXkMZMkD/vx+TNRSgUbWkVRBI08SqJg1K1wkFJtef8 s/VTyFNFrIsn5iNUbaSGNJOuFF+8fW1UwMIW8tEu7 X-Gm-Gg: ASbGncu3Eymlct9iCrE7lJU/+UkCzuMNnsL1PUcCRCiculRDlpsYmdsQl5SGY4rp3ne Npa9h3a+uYIjPHf/mB8Hqe2jglStibQx+uR5XmzIQoqtGz9U98A/L14nByQHZ2QiJgi5ajA3jsF 2rgBg9gx2w0gVyLX3B9F5+KEnwaHF76093ik1xb+O4Gf/R9I+JouXa1p2CWYWEy0/3tjvkxvivV DdjSNW7 X-Google-Smtp-Source: AGHT+IGJvynLQXA/LQk6fcdvOGBEcRDrc5pxDlC+y97uzcPtpCoY1GOnLHBKt5EXqBGMRmyPCzJQVsWFQZFmSoofD4Y= X-Received: by 2002:a05:600c:c174:b0:456:1752:2b44 with SMTP id 5b1f17b1804b1-4562e39126cmr18086275e9.23.1752659181173; Wed, 16 Jul 2025 02:46:21 -0700 (PDT) MIME-Version: 1.0 References: <20250715-align-min-allocator-v1-0-3e1b2a5516c0@google.com> <20250715-align-min-allocator-v1-2-3e1b2a5516c0@google.com> In-Reply-To: From: Alice Ryhl Date: Wed, 16 Jul 2025 11:46:08 +0200 X-Gm-Features: Ac12FXzX7ouyqpx1LVbRHdVZq8jMUt7yI_ccMl1Rky0bxaMou6U-Kfx8iWXzP3g Message-ID: Subject: Re: [PATCH 2/2] rust: alloc: take the allocator into account for FOREIGN_ALIGN To: Danilo Krummrich Cc: Lorenzo Stoakes , "Liam R. Howlett" , Andrew Morton , Matthew Wilcox , Tamir Duberstein , Andreas Hindborg , Miguel Ojeda , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Trevor Gross , 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-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E298B2000B X-Stat-Signature: s5qa1gr6j35xjjhd8xgp1ebc9zpq3tig X-Rspam-User: X-HE-Tag: 1752659182-251938 X-HE-Meta: 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 RvG9g//n 25i+ivuvPW+wk7nc57UABGZpgGhcQYUH75FbhXxtxPYfaVlN+eS604Mw7Yy5bstQU8QaBUeHY3dgqcknfF3KMKvDBks6TbH2gpri4JVTBPGGS2pWTEkVbBewxgcR182fWs3BTTrHDZYvjuXopOqiRwV463QAev7AlGfmrNNLeXeRb88cgKjvRyy0xrru9D1idcB0MJxIHr6H6CBHRlD6M7Wuy9uVah1LYUposzfzqCfWMFiDYpNohLRXLz26Dw/y/Oa8f1fx5fuK8VG+vpUS92ePfN2jz/3JOueZfCxcXwcGx+mSqdze3t2vrTRxpE07+nHVcOSlIqIgGZus= 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 Tue, Jul 15, 2025 at 4:19=E2=80=AFPM Danilo Krummrich = wrote: > > On Tue Jul 15, 2025 at 3:46 PM CEST, Alice Ryhl wrote: > > diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs > > index bffe72f44cb33a265018e67d92d9f0abe82f8e22..fd3f1e0b9c3b3437fb50d8f= 1b28c92bc7cefd565 100644 > > --- a/rust/kernel/alloc/kbox.rs > > +++ b/rust/kernel/alloc/kbox.rs > > @@ -400,12 +400,19 @@ fn try_init(init: impl Init, flags: Flag= s) -> Result > > } > > > > // SAFETY: The pointer returned by `into_foreign` comes from a well al= igned > > -// pointer to `T`. > > +// pointer to `T` allocated by `A`. > > unsafe impl ForeignOwnable for Box > > where > > A: Allocator, > > { > > - const FOREIGN_ALIGN: usize =3D core::mem::align_of::(); > > + const FOREIGN_ALIGN: usize =3D { > > + let mut align =3D core::mem::align_of::(); > > + if align < A::MIN_ALIGN { > > + align =3D A::MIN_ALIGN; > > + } > > + align > > + }; > > Pretty unfortunate that core::cmp::max() can't be used from const context= . :( > > What do you think about > > const FOREIGN_ALIGN: usize =3D > if core::mem::align_of::() < A::MIN_ALIGN { > A::MIN_ALIGN > } else { > core::mem::align_of::() > }; > > instead? I think that reads a bit better. I don't mind doing that instead. Alice