Re: [PATCH] mm/gup: Use put_user_page*() instead of put_page*()

[Bharath Vedartham]

On Mon, Jul 15, 2019 at 11:10:20AM -0700, John Hubbard wrote:
> On 7/14/19 11:56 PM, Bharath Vedartham wrote:
> > On Sun, Jul 14, 2019 at 04:33:42PM -0700, John Hubbard wrote:
> >> On 7/14/19 12:08 PM, Bharath Vedartham wrote:
> [...]
> >> 1. Pull down https://github.com/johnhubbard/linux/commits/gup_dma_core
> >> and find missing conversions: look for any additional missing 
> >> get_user_pages/put_page conversions. You've already found a couple missing 
> >> ones. I haven't re-run a search in a long time, so there's probably even more.
> >> 	a) And find more, after I rebase to 5.3-rc1: people probably are adding
> >> 	get_user_pages() calls as we speak. :)
> > Shouldn't this be documented then? I don't see any docs for using
> > put_user_page*() in v5.2.1 in the memory management API section?
> 
> Yes, it needs documentation. My first try (which is still in the above git
> repo) was reviewed and found badly wanting, so I'm going to rewrite it. Meanwhile,
> I agree that an interim note would be helpful, let me put something together.
> 
> [...]
> >>     https://github.com/johnhubbard/linux/commits/gup_dma_core
> >>
> >>     a) gets rebased often, and
> >>
> >>     b) has a bunch of commits (iov_iter and related) that conflict
> >>        with the latest linux.git,
> >>
> >>     c) has some bugs in the bio area, that I'm fixing, so I don't trust
> >>        that's it's safely runnable, for a few more days.
> > I assume your repo contains only work related to fixing gup issues and
> > not the main repo for gup development? i.e where gup changes are merged?
> 
> Correct, this is just a private tree, not a maintainer tree. But I'll try to
> keep the gup_dma_core branch something that is usable by others, during the
> transition over to put_user_page(), because the page-tracking patches are the
> main way to test any put_user_page() conversions.
> 
> As Ira said, we're using linux-mm as the real (maintainer) tree.
Thanks for the info! 
> 
> thanks,
> -- 
> John Hubbard
> NVIDIA