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From: Jason Gunthorpe <jgg@ziepe.ca>
To: john.hubbard@gmail.com
Cc: Matthew Wilcox <willy@infradead.org>,
	Michal Hocko <mhocko@kernel.org>,
	Christopher Lameter <cl@linux.com>,
	Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
	Al Viro <viro@zeniv.linux.org.uk>,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
	linux-rdma <linux-rdma@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>
Subject: Re: [PATCH 3/4] infiniband/mm: convert to the new put_user_page() call
Date: Fri, 28 Sep 2018 09:39:22 -0600
Message-ID: <20180928153922.GA17076@ziepe.ca> (raw)
In-Reply-To: <20180928053949.5381-3-jhubbard@nvidia.com>

On Thu, Sep 27, 2018 at 10:39:47PM -0700, john.hubbard@gmail.com wrote:
> From: John Hubbard <jhubbard@nvidia.com>
> 
> For code that retains pages via get_user_pages*(),
> release those pages via the new put_user_page(),
> instead of put_page().
> 
> This prepares for eventually fixing the problem described
> in [1], and is following a plan listed in [2].
> 
> [1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()"
> 
> [2] https://lkml.kernel.org/r/20180709080554.21931-1-jhubbard@nvidia.com
>     Proposed steps for fixing get_user_pages() + DMA problems.
> 
> CC: Doug Ledford <dledford@redhat.com>
> CC: Jason Gunthorpe <jgg@ziepe.ca>
> CC: Mike Marciniszyn <mike.marciniszyn@intel.com>
> CC: Dennis Dalessandro <dennis.dalessandro@intel.com>
> CC: Christian Benvenuti <benve@cisco.com>
> 
> CC: linux-rdma@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> CC: linux-mm@kvack.org
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
>  drivers/infiniband/core/umem.c              | 2 +-
>  drivers/infiniband/core/umem_odp.c          | 2 +-
>  drivers/infiniband/hw/hfi1/user_pages.c     | 2 +-
>  drivers/infiniband/hw/mthca/mthca_memfree.c | 6 +++---
>  drivers/infiniband/hw/qib/qib_user_pages.c  | 2 +-
>  drivers/infiniband/hw/qib/qib_user_sdma.c   | 8 ++++----
>  drivers/infiniband/hw/usnic/usnic_uiom.c    | 2 +-
>  7 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> index a41792dbae1f..9430d697cb9f 100644
> +++ b/drivers/infiniband/core/umem.c
> @@ -60,7 +60,7 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
>  		page = sg_page(sg);
>  		if (!PageDirty(page) && umem->writable && dirty)
>  			set_page_dirty_lock(page);
> -		put_page(page);
> +		put_user_page(page);

Would it make sense to have a release/put_user_pages_dirtied to absorb
the set_page_dity pattern too? I notice in this patch there is some
variety here, I wonder what is the right way?

Also, I'm told this code here is a big performance bottleneck when the
number of pages becomes very long (think >> GB of memory), so having a
future path to use some kind of batching/threading sound great.

Otherwise this RDMA part seems fine to me, there might be some minor
conflicts however. I assume you want to run this through the -mm tree?

Acked-by: Jason Gunthorpe <jgg@mellanox.com>

Jason

  reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-28  5:39 [PATCH 0/4] get_user_pages*() and RDMA: first steps john.hubbard
2018-09-28  5:39 ` [PATCH 1/4] mm: get_user_pages: consolidate error handling john.hubbard
2018-09-28  5:39 ` [PATCH 3/4] infiniband/mm: convert to the new put_user_page() call john.hubbard
2018-09-28 15:39   ` Jason Gunthorpe [this message]
2018-09-29  3:12     ` John Hubbard
2018-09-29 16:21       ` Matthew Wilcox
2018-09-29 19:19         ` Jason Gunthorpe
2018-10-01 12:50         ` Christoph Hellwig
2018-10-01 15:29           ` Matthew Wilcox
2018-10-01 15:51             ` Christoph Hellwig
2018-10-01 14:35       ` Dennis Dalessandro
2018-10-03  5:40         ` John Hubbard
2018-10-03 16:27       ` Jan Kara
2018-10-03 23:19         ` John Hubbard
2018-09-28  5:39 ` [PATCH 2/4] mm: introduce put_user_page(), placeholder version john.hubbard
2018-10-03 16:22   ` Jan Kara
2018-10-03 23:23     ` John Hubbard
2018-09-28  5:39 ` [PATCH 4/4] goldfish_pipe/mm: convert to the new release_user_pages() call john.hubbard
2018-09-28 15:29 ` [PATCH 0/4] get_user_pages*() and RDMA: first steps Jerome Glisse
2018-09-28 19:06   ` John Hubbard
2018-09-28 21:49     ` Jerome Glisse
2018-09-29  2:28       ` John Hubbard
2018-09-29  8:46         ` Jerome Glisse
2018-10-01  6:11           ` Dave Chinner
2018-10-01 12:47             ` Christoph Hellwig
2018-10-02  1:14               ` Dave Chinner
2018-10-03 16:21                 ` Jan Kara
2018-10-01 15:31             ` Jason Gunthorpe
2018-10-03 16:08           ` Jan Kara

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