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Date:   Fri, 11 Jun 2021 08:53:38 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ira Weiny <ira.weiny@intel.com>
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
Subject: Re: [PATCH 09/16] ps3disk: use memcpy_{from,to}_bvec
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On Tue, Jun 08, 2021 at 06:48:22PM -0700, Ira Weiny wrote:
> I'm still not 100% sure that these flushes are needed but the are not no-ops on
> every arch.  Would it be best to preserve them after the memcpy_to/from_bvec()?
> 
> Same thing in patch 11 and 14.

To me it seems kunmap_local should basically always call the equivalent
of flush_kernel_dcache_page.  parisc does this through
kunmap_flush_on_unmap, but none of the other architectures with VIVT
caches or other coherency issues does.

Does anyone have a history or other insights here?