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From: Linus Torvalds <torvalds@linux-foundation.org>
To: ojeda@kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	rust-for-linux@vger.kernel.org,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alex Gaynor <alex.gaynor@gmail.com>,
	Geoffrey Thomas <geofft@ldpreload.com>,
	Finn Behrens <me@kloenk.de>,
	Adam Bratschi-Kaye <ark.email@gmail.com>,
	Wedson Almeida Filho <wedsonaf@google.com>,
	Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [PATCH 07/13] Rust: Kernel crate
Date: Wed, 14 Apr 2021 12:31:10 -0700
Message-ID: <CAHk-=wiVY56LzwV_G075NEFwsdf-p7GOTy_cB7-UU9b=49rB1g@mail.gmail.com> (raw)
In-Reply-To: <20210414184604.23473-8-ojeda@kernel.org>

On Wed, Apr 14, 2021 at 11:47 AM <ojeda@kernel.org> wrote:
>
> +#[alloc_error_handler]
> +fn oom(_layout: Layout) -> ! {
> +    panic!("Out of memory!");
> +}
> +
> +#[no_mangle]
> +pub fn __rust_alloc_error_handler(_size: usize, _align: usize) -> ! {
> +    panic!("Out of memory!");
> +}

Again, excuse my lack of internal Rust knowledge, but when do these
end up being an issue?

If the Rust compiler ends up doing hidden allocations, and they then
cause panics, then one of the main *points* of Rustification is
entirely broken. That's 100% the opposite of being memory-safe at
build time.

An allocation failure in some random driver must never ever be
something that the compiler just turns into a panic. It must be
something that is caught and handled synchronously and results in an
ENOMEM error return.

So the fact that the core patches have these kinds of

    panic!("Out of memory!");

things in them as part of just the support infrastructure makes me go
"Yeah, that's fundamentally wrong".

And if this is some default that is called only when the Rust code
doesn't have error handling, then once again - I think it needs to be
a *build-time* failure, not a runtime one. Because having unsafe code
that will cause a panic only under very special situations that are
hard to trigger is about the worst possible case.

             Linus

  reply index

Thread overview: 183+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-14 18:45 [PATCH 00/13] [RFC] Rust support ojeda
2021-04-14 18:45 ` [PATCH 01/13] kallsyms: Support "big" kernel symbols (2-byte lengths) ojeda
2021-04-14 19:44   ` Matthew Wilcox
2021-04-14 19:59     ` Miguel Ojeda
2021-04-14 18:45 ` [PATCH 02/13] kallsyms: Increase maximum kernel symbol length to 512 ojeda
2021-04-14 23:48   ` Nick Desaulniers
2021-04-14 18:45 ` [PATCH 03/13] Makefile: Generate CLANG_FLAGS even in GCC builds ojeda
2021-04-14 18:59   ` Nathan Chancellor
2021-04-15 10:18     ` Miguel Ojeda
2021-04-14 23:46   ` Nick Desaulniers
2021-04-15  0:47     ` Miguel Ojeda
2021-04-14 18:45 ` [PATCH 04/13] Kbuild: Rust support ojeda
2021-04-14 23:19   ` Nick Desaulniers
2021-04-15  0:43     ` Miguel Ojeda
2021-04-15 18:03       ` Nick Desaulniers
2021-04-16 12:23         ` Miguel Ojeda
2021-04-17 19:35       ` Masahiro Yamada
2021-04-16 13:38   ` Peter Zijlstra
2021-04-16 17:05     ` Linus Torvalds
2021-04-16 17:47       ` Miguel Ojeda
2021-04-16 18:09         ` Al Viro
2021-04-16 18:57           ` Miguel Ojeda
2021-04-16 20:22             ` Willy Tarreau
2021-04-16 20:34               ` Connor Kuehl
2021-04-16 20:58                 ` Willy Tarreau
2021-04-16 21:39                   ` Miguel Ojeda
2021-04-16 22:04                     ` Willy Tarreau
2021-04-16 22:45                       ` Al Viro
2021-04-16 23:46                       ` Miguel Ojeda
2021-04-17  4:24                         ` Willy Tarreau
2021-04-17 15:38                           ` Miguel Ojeda
2021-04-16 21:19               ` Miguel Ojeda
2021-04-16 17:34     ` Miguel Ojeda
2021-04-19 19:58       ` David Sterba
2021-04-19 20:17         ` Matthew Wilcox
2021-04-19 21:03           ` Miguel Ojeda
2021-04-19 20:54         ` Miguel Ojeda
2021-04-14 18:45 ` [PATCH 05/13] Rust: Compiler builtins crate ojeda
2021-04-14 19:19   ` Linus Torvalds
2021-04-14 19:34     ` Miguel Ojeda
2021-04-14 18:45 ` [PATCH 06/13] Rust: Module crate ojeda
2021-04-14 18:45 ` [PATCH 07/13] Rust: Kernel crate ojeda
2021-04-14 19:31   ` Linus Torvalds [this message]
2021-04-14 19:50     ` Miguel Ojeda
2021-04-14 18:45 ` [PATCH 08/13] Rust: Export generated symbols ojeda
2021-04-14 18:46 ` [PATCH 09/13] Samples: Rust examples ojeda
2021-04-14 19:34   ` Linus Torvalds
2021-04-14 19:42     ` Miguel Ojeda
2021-04-14 19:49       ` Matthew Wilcox
2021-04-16 11:46       ` Andrej Shadura
2021-04-14 23:24     ` Nick Desaulniers
2021-04-15  7:10       ` Greg Kroah-Hartman
2021-04-15  7:39         ` Nick Desaulniers
2021-04-15 12:42         ` Miguel Ojeda
2021-04-16 13:07         ` Sven Van Asbroeck
2021-04-16 13:20           ` Greg Kroah-Hartman
2021-04-14 18:46 ` [PATCH 10/13] Documentation: Rust general information ojeda
2021-04-14 22:17   ` Nick Desaulniers
2021-04-14 23:34     ` Miguel Ojeda
2021-04-14 18:46 ` [PATCH 11/13] MAINTAINERS: Rust ojeda
2021-04-14 21:55   ` Nick Desaulniers
2021-04-14 22:02     ` Miguel Ojeda
2021-04-14 22:36   ` Nick Desaulniers
2021-04-14 18:46 ` [PATCH 12/13] Rust: add abstractions for Binder (WIP) ojeda
2021-04-14 18:46 ` [PATCH 13/13] Android: Binder IPC in Rust (WIP) ojeda
2021-04-14 19:44 ` [PATCH 00/13] [RFC] Rust support Linus Torvalds
2021-04-14 20:20   ` Miguel Ojeda
2021-04-15  1:38     ` Kees Cook
2021-04-15  8:26       ` David Laight
2021-04-15 18:08         ` Kees Cook
2021-04-15 12:39       ` Miguel Ojeda
2021-04-14 20:09 ` Matthew Wilcox
2021-04-14 20:21   ` Linus Torvalds
2021-04-14 20:35     ` Josh Triplett
2021-04-14 22:08     ` David Laight
2021-04-14 20:29   ` Miguel Ojeda
2021-04-18 15:31   ` Wedson Almeida Filho
2021-04-15  0:22 ` Nick Desaulniers
2021-04-15 10:05   ` Miguel Ojeda
2021-04-15 18:58 ` Peter Zijlstra
2021-04-16  2:22   ` Wedson Almeida Filho
2021-04-16  4:25     ` Al Viro
2021-04-16  5:02       ` Wedson Almeida Filho
2021-04-16  5:39         ` Paul Zimmerman
2021-04-16  7:46         ` Peter Zijlstra
2021-04-16  7:09     ` Peter Zijlstra
2021-04-17  5:23       ` comex
2021-04-17 12:46       ` David Laight
2021-04-17 14:51       ` Paolo Bonzini
2021-04-19  7:32         ` Peter Zijlstra
2021-04-19  7:53           ` Paolo Bonzini
2021-04-19  8:26             ` Peter Zijlstra
2021-04-19  8:35               ` Peter Zijlstra
2021-04-19  9:02               ` Paolo Bonzini
2021-04-19  9:36                 ` Peter Zijlstra
2021-04-19  9:40                   ` Paolo Bonzini
2021-04-19 11:01                     ` Will Deacon
2021-04-19 17:14                   ` Linus Torvalds
2021-04-19 18:38                     ` Paolo Bonzini
2021-04-19 18:50                       ` Linus Torvalds
2021-04-22 10:03     ` Linus Walleij
2021-04-22 14:09       ` David Laight
2021-04-22 15:24       ` Wedson Almeida Filho
2021-04-26  0:18         ` Linus Walleij
2021-04-26 14:26           ` Miguel Ojeda
2021-04-26 14:40           ` Wedson Almeida Filho
2021-04-26 16:03             ` Miguel Ojeda
2021-04-27 10:54             ` Linus Walleij
2021-04-27 11:13               ` Robin Randhawa
2021-04-29  1:52               ` Wedson Almeida Filho
2021-04-26 18:01           ` Miguel Ojeda
2021-04-22 21:28       ` Miguel Ojeda
2021-04-26  0:31         ` Linus Walleij
2021-04-26 18:18           ` Miguel Ojeda
2021-04-27 11:13             ` Linus Walleij
2021-04-28  2:51               ` Kyle Strand
2021-04-28  3:10               ` Miguel Ojeda
2021-05-04 21:21                 ` Linus Walleij
2021-05-04 23:30                   ` Miguel Ojeda
2021-05-05 11:34                     ` Linus Walleij
2021-05-05 14:17                       ` Miguel Ojeda
2021-05-05 15:13                         ` Enrico Weigelt, metux IT consult
2021-05-06 12:47                         ` Linus Walleij
2021-05-07 18:23                           ` Miguel Ojeda
2021-04-16  4:27   ` Boqun Feng
2021-04-16  6:04     ` Nick Desaulniers
2021-04-16 18:47       ` Paul E. McKenney
2021-04-19 20:35         ` Nick Desaulniers
2021-04-19 21:37           ` Paul E. McKenney
2021-04-19 22:03           ` Miguel Ojeda
2021-04-16 20:48     ` Josh Triplett
2021-04-16  8:16   ` Michal Kubecek
2021-04-16  9:29     ` Willy Tarreau
2021-04-16 11:24 ` Peter Zijlstra
2021-04-16 13:07   ` Wedson Almeida Filho
2021-04-16 14:19     ` Peter Zijlstra
2021-04-16 15:04       ` Miguel Ojeda
2021-04-16 15:43         ` Peter Zijlstra
2021-04-16 16:21           ` Miguel Ojeda
2021-04-16 15:33       ` Wedson Almeida Filho
2021-04-16 16:14         ` Willy Tarreau
2021-04-16 17:10           ` Miguel Ojeda
2021-04-16 17:18             ` Peter Zijlstra
2021-04-16 18:08               ` Matthew Wilcox
2021-04-17 11:17                 ` Peter Zijlstra
2021-04-17 11:46                   ` Willy Tarreau
2021-04-17 14:24                     ` Peter Zijlstra
2021-04-17 14:36                       ` Willy Tarreau
2021-04-17 13:46                   ` David Laight
2021-04-16 17:37             ` Willy Tarreau
2021-04-16 17:46               ` Connor Kuehl
2021-04-20  0:24               ` Nick Desaulniers
2021-04-20  3:47                 ` Willy Tarreau
2021-04-20  5:56                 ` Greg Kroah-Hartman
2021-04-20  6:16                   ` Willy Tarreau
2021-04-29 15:38                     ` peter enderborg
2021-04-17 13:53           ` Wedson Almeida Filho
2021-04-17 14:21             ` Willy Tarreau
2021-04-17 15:23               ` Miguel Ojeda
2021-04-18 15:51               ` Wedson Almeida Filho
2021-04-17 12:41       ` David Laight
2021-04-17 13:01         ` Wedson Almeida Filho
2021-04-16 15:03     ` Matthew Wilcox
2021-04-17 13:29       ` Wedson Almeida Filho
2021-04-16 15:58     ` Theodore Ts'o
2021-04-16 16:21       ` Wedson Almeida Filho
2021-04-17 15:11       ` Paolo Bonzini
2021-04-16 14:21   ` Miguel Ojeda
2021-04-17 20:42 ` Richard Weinberger
2021-04-28 18:34 ` Mariusz Ceier
2021-04-28 20:25   ` Nick Desaulniers
2021-04-28 21:21   ` David Laight
2021-04-29 11:14     ` Kajetan Puchalski
2021-04-29 11:25   ` Kajetan Puchalski
2021-04-29 14:06     ` Mariusz Ceier
2021-04-29 14:13       ` Sven Van Asbroeck
2021-04-29 14:26         ` Willy Tarreau
2021-04-29 15:06       ` Al Viro
2021-04-29 16:09         ` Mariusz Ceier
2021-04-30  6:39     ` Thomas Schoebel-Theuer
2021-04-30  8:30       ` David Laight
2021-05-05 13:58       ` Enrico Weigelt, metux IT consult
2021-05-05 14:41         ` Miguel Ojeda

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