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Date:   Wed, 7 Sep 2022 18:07:31 -0700
From:   Dan Williams <dan.j.williams@intel.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Davidlohr Bueso <dave@stgolabs.net>
CC:     <dan.j.williams@intel.com>, <x86@kernel.org>,
        <nvdimm@lists.linux.dev>, <linux-cxl@vger.kernel.org>,
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        <ira.weiny@intel.com>, <a.manzanares@samsung.com>,
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Subject: Re: [PATCH -next] memregion: Add arch_flush_memregion() interface
Message-ID: <631940536d040_2736529437@dwillia2-xfh.jf.intel.com.notmuch>
References: <20220829212918.4039240-1-dave@stgolabs.net>
 <20220907153016.f7cd4f42a337fedae8319f28@linux-foundation.org>
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Andrew Morton wrote:
> I really dislike the term "flush".  Sometimes it means writeback,
> sometimes it means invalidate.  Perhaps at other times it means
> both.
> 
> Can we please be very clear in comments and changelogs about exactly
> what this "flush" does.   With bonus points for being more specific in the 
> function naming?
> 

That's a good point, "flush" has been cargo-culted along in Linux's
cache management APIs to mean write-back-and-invalidate. In this case I
think this API is purely about invalidate. It just so happens that x86
has not historically had a global invalidate instruction readily
available which leads to the overuse of wbinvd.

It would be nice to make clear that this API is purely about
invalidating any data cached for a physical address impacted by address
space management event (secure erase / new region provision). Write-back
is an unnecessary side-effect.

So how about:

s/arch_flush_memregion/cpu_cache_invalidate_memregion/?