From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgg@mellanox.com>
Subject: Re: [PATCH 1/1] infiniband/mm: convert put_page() to put_user_page*()
Date: Thu, 23 May 2019 17:32:26 +0000
Message-ID: <20190523173222.GH12145@mellanox.com>
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To: Ira Weiny <ira.weiny@intel.com>
Cc: "john.hubbard@gmail.com" <john.hubbard@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, "linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>, "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, John Hubbard <jhubbard@nvidia.com>, Doug Ledford <dledford@redhat.com>, Mike Marciniszyn <mike.marciniszyn@intel.com>, Dennis Dalessandro <dennis.dalessandro@intel.com>, Christian Benvenuti <benve@cisco.com>, Jan Kara <jack@suse.cz>
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On Thu, May 23, 2019 at 10:28:52AM -0700, Ira Weiny wrote:
> > =20
> > @@ -686,8 +686,8 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *u=
mem_odp, u64 user_virt,
> >  			 * ib_umem_odp_map_dma_single_page().
> >  			 */
> >  			if (npages - (j + 1) > 0)
> > -				release_pages(&local_page_list[j+1],
> > -					      npages - (j + 1));
> > +				put_user_pages(&local_page_list[j+1],
> > +					       npages - (j + 1));
>=20
> I don't know if we discussed this before but it looks like the use of
> release_pages() was not entirely correct (or at least not necessary) here=
.  So
> I think this is ok.

Oh? John switched it from a put_pages loop to release_pages() here:

commit 75a3e6a3c129cddcc683538d8702c6ef998ec589
Author: John Hubbard <jhubbard@nvidia.com>
Date:   Mon Mar 4 11:46:45 2019 -0800

    RDMA/umem: minor bug fix in error handling path
   =20
    1. Bug fix: fix an off by one error in the code that cleans up if it fa=
ils
       to dma-map a page, after having done a get_user_pages_remote() on a
       range of pages.
   =20
    2. Refinement: for that same cleanup code, release_pages() is better th=
an
       put_page() in a loop.
   =20

And now we are going to back something called put_pages() that
implements the same for loop the above removed?

Seems like we are going in circles?? John?

Jason