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Date:   Tue, 22 Sep 2020 08:22:49 +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
Message-ID: <20200922062249.GA30831@lst.de>
References: <20200918163724.2511-1-hch@lst.de> <20200918163724.2511-4-hch@lst.de> <20200921191157.GX32101@casper.infradead.org>
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On Mon, Sep 21, 2020 at 08:11:57PM +0100, Matthew Wilcox wrote:
> This is awkward.  I'd like it if we had a vfree() variant which called
> put_page() instead of __free_pages().  I'd like it even more if we
> used release_pages() instead of our own loop that called put_page().

Note that we don't need a new vfree variant, we can do this manually if
we want, take a look at kernel/dma/remap.c.  But I thought this code
intentionally doesn't want to do that to avoid locking in the memory
for the pages array.  Maybe the i915 maintainers can clarify.