linux-kernel - Re: [PATCH v2 03/46] mm: Add kmap_local

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Message-ID: <YNLpvO4baPikgvc5@infradead.org>
Date:   Wed, 23 Jun 2021 09:58:52 +0200
From:   Christoph Hellwig <hch@...radead.org>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 03/46] mm: Add kmap_local_folio()

On Tue, Jun 22, 2021 at 01:15:08PM +0100, Matthew Wilcox (Oracle) wrote:
> This allows us to map a portion of a folio.  Callers can only expect
> to access up to the next page boundary.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

This looks sensible to me:

Reviewed-by: Christoph Hellwig <hch@....de>

While we're at it:  flushing incoherent mappings for use with kmap
has been a complete mess.  I've been trying to fix this with
kunmap_local_dirty, but that could use another review, as well as a
folio version probably give that one prime use case of folios is to have
them mapped into userspace.