linux-kernel - Re: [PATCH 07/10] crypto: Use ARCH_DMA_MINALIGN instead of ARCH_KMALLOC

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Message-ID: <Yzc2UrX7ndWw1vKI@arm.com>
Date:   Fri, 30 Sep 2022 19:32:50 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Isaac Manjarres <isaacmanjarres@...gle.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Ard Biesheuvel <ardb@...nel.org>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Saravana Kannan <saravanak@...gle.com>, kernel-team@...roid.com
Subject: Re: [PATCH 07/10] crypto: Use ARCH_DMA_MINALIGN instead of
 ARCH_KMALLOC_MINALIGN

On Tue, Sep 20, 2022 at 05:47:33PM -0700, Isaac Manjarres wrote:
> On Mon, Jul 18, 2022 at 06:53:43PM +0100, Catalin Marinas wrote:
> > So do I but holidays get in the way ;). I plan to refresh my kmalloc
> > minalign series at the end of August.
> > 
> > One significant change I have though is that now ARCH_KMALLOC_MINALIGN
> > now goes down all the way to 8 and using swiotlb bounce buffering if the
> > DMA mapping size is small.
> 
> This sounds like a good idea for optimizing kmalloc's memory usage
> beyond what this series originally achieved. I'm sure a few other things
> have come up in the meantime, but I was curious to know if you had a
> chance to get back to this?

I started refreshing the series but I got stuck on having to do bouncing
for small buffers even if when they go through the iommu (and I don't
have the set up to test it yet).

I hope to post something when the merging window closes. In the
meantime, I pushed my work-in-progress patches to:

git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux devel/kmalloc-minalign-v2-wip

Apart from the iommu think, I still need to figure out whether with an
ARCH_DMA_MINALIGN of 128 we need to disable the kmalloc-192 cache (so
far I don't think it's needed). There are no additional changes to the
crypto code from the last series, I still set CRYPTO_MINALIGN to
ARCH_DMA_MINALIGN (without any other patches, crypto DMA will break; so
I need to see how it interacts with Herbert's series).

Anyway, I hope for more discussions once 6.1-rc1 is out.

-- 
Catalin