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

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Date:   Sat, 10 Jun 2023 09:41:28 +0100
From:   Giovanni Cabiddu <giovanni.cabiddu@...el.com>
To:     Eric Biggers <ebiggers@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>
CC:     "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 Fri, Jun 09, 2023 at 05:24:04PM +0800, Herbert Xu wrote:
> 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.
If you all agree, I can send a patch to remove CRYPTO_ALG_ALLOCATES_MEMORY
from dm-integrity and update the documentation in crypto.h.

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

Regards,

-- 
Giovanni