linux-kernel - Re: [PATCH 0/5] Remove CRYPTO_ALG_ALLOCATES

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Message-ID: <ZILvtASXQKLG43y9@gondor.apana.org.au>
Date:   Fri, 9 Jun 2023 17:24:04 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Giovanni Cabiddu <giovanni.cabiddu@...el.com>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        "meenakshi.aggarwal@....com" <meenakshi.aggarwal@....com>,
        "horia.geanta@....com" <horia.geanta@....com>,
        "V.sethi@....com" <V.sethi@....com>,
        "pankaj.gupta@....com" <pankaj.gupta@....com>,
        "gaurav.jain@....com" <gaurav.jain@....com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iuliana.prodan@....com" <iuliana.prodan@....com>,
        lucas.segarra.fernandez@...el.com
Subject: Re: [PATCH 0/5] Remove CRYPTO_ALG_ALLOCATES_MEMORY flag

On Thu, Jun 01, 2023 at 12:23:58PM +0100, Giovanni Cabiddu wrote:
>
> BTW, some time ago we did an assessment of the users of
> !CRYPTO_ALG_ALLOCATES_MEMORY and we came to the conclusion that we
> cannot just update the documentation.
> dm-crypt uses scatterlists with at most 4 entries. dm-integrity,
> instead, might allocate memory for scatterlists with an arbitrary number
> of entries.

dm-integrity shouldn't be using ALLOCATES_MEMORY at all.  It's
using GFP_KERNEL allocations right next to the crypto operations.

But those are some seriously big crypto operations, 16 thousand
4K pages in one hit?

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt