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From: Al Viro <viro@ZenIV.linux.org.uk>
To: Lorenzo Stoakes <lstoakes@gmail.com>,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-mm@kvack.org
Subject: Re: [PATCH RESEND] drm/via: use get_user_pages_unlocked()
Date: Tue, 28 Feb 2017 19:35:39 +0000	[thread overview]
Message-ID: <20170228193539.GT29622@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20170228090110.m4pxtjlbgaft7oet@phenom.ffwll.local>

On Tue, Feb 28, 2017 at 10:01:10AM +0100, Daniel Vetter wrote:

> > +	ret = get_user_pages_unlocked((unsigned long)xfer->mem_addr,
> > +			vsg->num_pages, vsg->pages,
> > +			(vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0);

Umm...  Why not
	ret = get_user_pages_fast((unsigned long)xfer->mem_addr,
			vsg->num_pages,
			vsg->direction == DMA_FROM_DEVICE,
			vsg->pages);

IOW, do you really need a warranty that ->mmap_sem will be grabbed and
released?

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  reply	other threads:[~2017-02-28 19:35 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-27 21:50 Lorenzo Stoakes
2017-02-28  9:01 ` Daniel Vetter
2017-02-28 19:35   ` Al Viro [this message]
2017-02-28 20:28     ` Lorenzo Stoakes
2017-03-01  8:43       ` Daniel Vetter

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