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b=es+ldT/DqHjprxUm+UD9M9GM87UABh2Z+TIJRVfV5qW23yzi1t/USl4Ol43ux+hc6 s33vQxJpkyG90VhNtPvLA06fNvJYw2g1ia8GM/eBSsWu+mfIlXXxvGVa/HZLYUOGjr dI3otS8ndT9ywKNAx88NfaHHiIfkz5Es6LVdv3GC2uhzus76fM35UMRXoi7b0pL8aM OGGsovThVWJrvcUVhYXSgfnS3YdLVJat6rixCqxqrHhq7MJFHzoDSUMiNsEIQNw7ta aKm+GLnGP1eGosY9Pnpn8zgiGMfyfJ0I5HRRJNLoJHZSSaezTAzW7XOVv2hCqHuycl NyMRv4NoBqRuQ== Date: Wed, 14 Aug 2024 19:13:12 +0200 From: Danilo Krummrich To: Benno Lossin Cc: ojeda@kernel.org, alex.gaynor@gmail.com, wedsonaf@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, a.hindborg@samsung.com, aliceryhl@google.com, akpm@linux-foundation.org, daniel.almeida@collabora.com, faith.ekstrand@collabora.com, boris.brezillon@collabora.com, lina@asahilina.net, mcanal@igalia.com, zhiw@nvidia.com, cjia@nvidia.com, jhubbard@nvidia.com, airlied@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v5 04/26] rust: alloc: implement `Allocator` for `Kmalloc` Message-ID: References: <20240812182355.11641-1-dakr@kernel.org> <20240812182355.11641-5-dakr@kernel.org> <04b0fd96-c91c-4f38-90e9-8acee31e8445@proton.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <04b0fd96-c91c-4f38-90e9-8acee31e8445@proton.me> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 07CADC0014 X-Stat-Signature: p16c9bp6n9hw15z5h7ooibn7h3fkpxog X-Rspam-User: X-HE-Tag: 1723655601-984989 X-HE-Meta: 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 GP/+U7+e snD9TXRCRh7efWzM6i2nN0HLVgcgG6vIJ/eurTYwXuzqCLHenbQ+8mCTLxDk0smLu3v0RKasde2GO/K2APB8tp33V5W5Ex5sKw+y5RqY9F+Pvn3DQOSdDHMtjRDYiI4GfCp7ifIesbsA6riOIDhv3Fk/sv9IOoOLlpSQpbjzss8YofT2aRTs9HuO00/08lUtq67A1yFC5aU+Js6/qQv+gns0+u0a+xb6AI0wVS3nmFdkI0o2+6kCiafCAvnUwRnZsZPWV1fmIpeprM6lRNIfEHWoqylfJnX7yVb9OIc1FmMRNlpk= 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 Wed, Aug 14, 2024 at 04:28:04PM +0000, Benno Lossin wrote: > On 12.08.24 20:22, Danilo Krummrich wrote: > > +unsafe impl Allocator for Kmalloc { > > There is a missing SAFETY comment here (and also for Vmalloc, probably > also for VKmalloc then). Any suggestion on what to write here? I'd probably come up with something like: -- Memory returned from `Kmalloc` remains valid until explicitly freed. It is valid to pass any pointer to an allocated memory buffer obtained with any function of `Kmalloc` to any other function of `Kmalloc`. If `Kmalloc::realloc` is called with a size of zero, the given memory allocation, if any, is freed. If `Kmalloc::realloc` is called with `None` it behaves like `Kmalloc::alloc`, i.e. a new memory allocation is created. -- and repeat that for `Vmalloc` and `KVmalloc`. I'm not sure how useful that is though. > > --- > Cheers, > Benno > > > + unsafe fn realloc( > > + ptr: Option>, > > + layout: Layout, > > + flags: Flags, > > + ) -> Result, AllocError> { > > + // SAFETY: `ReallocFunc::call` has the same safety requirements as `Allocator::realloc`. > > + unsafe { ReallocFunc::KREALLOC.call(ptr, layout, flags) } > > + } > > +} > > + > > unsafe impl GlobalAlloc for Kmalloc { > > unsafe fn alloc(&self, layout: Layout) -> *mut u8 { > > // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety > > -- > > 2.45.2 > > >