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Date:   Tue, 22 Sep 2020 16:39:06 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Andrew Morton <akpm@linux-foundation.org>,
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Subject: Re: [PATCH 3/6] drm/i915: use vmap in shmem_pin_map
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References: <20200918163724.2511-1-hch@lst.de> <20200918163724.2511-4-hch@lst.de> <20200921191157.GX32101@casper.infradead.org> <20200922062249.GA30831@lst.de> <20200922112144.GB32101@casper.infradead.org>
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On Tue, Sep 22, 2020 at 12:21:44PM +0100, Matthew Wilcox wrote:
> Actually, vfree() will work today; I cc'd you on a documentation update
> to make it clear that this is permitted.

vfree calls __free_pages, the i915 and a lot of other code calls
put_page.  They are mostly the same, but not quite and everytime I
look into that mess I'm more confused than before.

Can someone in the know write sensible documentation on when to use
__free_page(s) vs put_page?