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Date:   Mon, 9 Jan 2023 15:37:33 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>
Subject: Re: [PATCH] crypto: talitos - Remove GFP_DMA and add DMA alignment
 padding
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On Mon, Jan 09, 2023 at 07:18:27AM +0000, Christophe Leroy wrote:
>
> Doesn't GFP_DMA guarantees that the provided memory is addressable for 
> DMA ? Or do we assume that all memory returned by kmalloc can be used 
> for DMA ?

No it does not.  Please refer to the DMI API documentation.

> kmalloc() already returns not DMA aligned memory, why does it becomes a 
> problem now ?

As it stands kmalloc on arm64 returns DMA-aligned memory.  This
will soon no longer be the case.

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