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Date:   Tue, 15 Jun 2021 13:02:59 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Ira Weiny <ira.weiny@intel.com>,
        "David S. Miller" <davem@davemloft.net>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Geoff Levand <geoff@infradead.org>,
        Ilya Dryomov <idryomov@gmail.com>,
        Dongsheng Yang <dongsheng.yang@easystack.cn>,
        Mike Snitzer <snitzer@redhat.com>, dm-devel@redhat.com,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-block@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        ceph-devel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        linux-arch@vger.kernel.org, Tero Kristo <t-kristo@ti.com>,
        linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
        linux-sh@vger.kernel.org, linux-mmc@vger.kernel.org,
        linux-scsi@vger.kernel.org
Subject: Re: [PATCH 09/16] ps3disk: use memcpy_{from,to}_bvec
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On Fri, Jun 11, 2021 at 09:07:43PM -0700, Ira Weiny wrote:
>
> More recently this was added:
> 
> 7e34e0bbc644 crypto: omap-crypto - fix userspace copied buffer access
> 
> I'm CC'ing Tero and Herbert to see why they added the SLAB check.

Probably because the generic Crypto API has the same check.  This
all goes back to

commit 4f3e797ad07d52d34983354a77b365dfcd48c1b4
Author: Herbert Xu <herbert@gondor.apana.org.au>
Date:   Mon Feb 9 14:22:14 2009 +1100

    crypto: scatterwalk - Avoid flush_dcache_page on slab pages

    It's illegal to call flush_dcache_page on slab pages on a number
    of architectures.  So this patch avoids doing so if PageSlab is
    true.

    In future we can move the flush_dcache_page call to those page
    cache users that actually need it.

    Reported-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

But I can't find any emails discussing this so let me ask Dave
directly and see if he can tell us what the issue was or might
have been.

Thanks,
-- 
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