Re: [PATCH v3 1/1] mm: introduce put_user_page*(), placeholder versions

[John Hubbard]

On 3/13/19 7:49 AM, Ira Weiny wrote:
> On Tue, Mar 12, 2019 at 05:38:55PM -0700, John Hubbard wrote:
> > On 3/12/19 8:30 AM, Ira Weiny wrote:
> > > On Wed, Mar 06, 2019 at 03:54:55PM -0800, john.hubbard@xxxxxxxxx wrote:
> > > > From: John Hubbard <jhubbard@xxxxxxxxxx>
> > > >
> > > > Introduces put_user_page(), which simply calls put_page().
> > > > This provides a way to update all get_user_pages*() callers,
> > > > so that they call put_user_page(), instead of put_page().
> > >
> > > So I've been running with these patches for a while but today while ramping up
> > > my testing I hit the following:
> > >
> > > [ 1355.557819] ------------[ cut here ]------------
> > > [ 1355.563436] get_user_pages pin count overflowed
> >
> > Hi Ira,
> >
> > Thanks for reporting this. That overflow, at face value, means that we've
> > used more than the 22 bits worth of gup pin counts, so about 4 million pins
> > of the same page...
>
> This is my bug in the patches I'm playing with.  Somehow I'm causing more puts
> than gets...  I'm not sure how but this is for sure my problem.
>
> Backing off to your patch set the numbers are good.

Now that's a welcome bit of good news!

> Sorry for the noise.
>
> With the testing I've done today I feel comfortable adding
>
> Tested-by: Ira Weiny <ira.weiny@xxxxxxxxx>
>
> For the main GUP and InfiniBand patches.
>
> Ira

OK, I'll add your tested-by tag to patches 1, 2, 4, 5 (the numbering refers
to the "RFC v2: mm: gup/dma tracking" posting [1]) in my repo [2], and they'll 
show up in the next posting. (Patch 3 is already upstream, and patch 6 is
documentation that needs to be rewritten entirely.)

[1] https://lore.kernel.org/r/20190204052135.25784-1-jhubbard@xxxxxxxxxx

[2] https://github.com/johnhubbard/linux/tree/gup_dma_core

thanks,
--
John Hubbard
NVIDIA