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From: David Laight <David.Laight@ACULAB.COM>
To: "'y86-dev@protonmail.com'" <y86-dev@protonmail.com>,
	"Miguel Ojeda" <ojeda@kernel.org>,
	"Alex Gaynor" <alex.gaynor@gmail.com>,
	"Wedson Almeida Filho" <wedsonaf@gmail.com>,
	"Boqun Feng" <boqun.feng@gmail.com>,
	"Gary Guo" <gary@garyguo.net>,
	"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
	"Alice Ryhl" <alice@ryhl.io>
Cc: "rust-for-linux@vger.kernel.org" <rust-for-linux@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"patches@lists.linux.dev" <patches@lists.linux.dev>
Subject: RE: [PATCH v3 12/13] rust: sync: reduce stack usage of `UniqueArc::try_new_uninit`
Date: Thu, 30 Mar 2023 14:58:24 +0000	[thread overview]
Message-ID: <7f55875c46ab4c4989323ede57f6e46d@AcuMS.aculab.com> (raw)
In-Reply-To: <20230329223239.138757-13-y86-dev@protonmail.com>

From: y86-dev@protonmail.com
> Sent: 29 March 2023 23:34
> 
> `UniqueArc::try_new_uninit` calls `Arc::try_new(MaybeUninit::uninit())`.
> This results in the uninitialized memory being placed on the stack,
> which may be arbitrarily large due to the generic `T` and thus could
> cause a stack overflow for large types.

Does that mean rust is using (the equivalent of) alloca() ?

That is banned for C code in the kernel for any sizes.

	David

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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)

  parent reply	other threads:[~2023-03-30 14:59 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-29 22:33 y86-dev
2023-03-30 11:08 ` Gary Guo
2023-03-30 14:58 ` David Laight [this message]
2023-03-30 15:16   ` Benno Lossin
2023-03-31  7:05 ` Alice Ryhl
2023-03-31 13:03 ` Andreas Hindborg

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