Messages in this thread | | | Date | Mon, 8 Oct 2018 18:49:07 +0200 | From | Jan Kara <> | Subject | Re: [PATCH v3 2/3] mm: introduce put_user_page*(), placeholder versions |
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On Fri 05-10-18 19:49:48, john.hubbard@gmail.com wrote: > From: John Hubbard <jhubbard@nvidia.com> > > 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(). > > Also introduces put_user_pages(), and a few dirty/locked variations, > as a replacement for release_pages(), and also as a replacement > for open-coded loops that release multiple pages. > These may be used for subsequent performance improvements, > via batching of pages to be released. > > This prepares for eventually fixing the problem described > in [1], and is following a plan listed in [2], [3], [4]. > > [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. > > [3]https://lkml.kernel.org/r/20180710082100.mkdwngdv5kkrcz6n@quack2.suse.cz > Bounce buffers (otherwise [2] is not really viable). > > [4] https://lkml.kernel.org/r/20181003162115.GG24030@quack2.suse.cz > Follow-up discussions. > > CC: Matthew Wilcox <willy@infradead.org> > CC: Michal Hocko <mhocko@kernel.org> > CC: Christopher Lameter <cl@linux.com> > CC: Jason Gunthorpe <jgg@ziepe.ca> > CC: Dan Williams <dan.j.williams@intel.com> > CC: Jan Kara <jack@suse.cz> > CC: Al Viro <viro@zeniv.linux.org.uk> > CC: Jerome Glisse <jglisse@redhat.com> > CC: Christoph Hellwig <hch@infradead.org> > CC: Ralph Campbell <rcampbell@nvidia.com> > Signed-off-by: John Hubbard <jhubbard@nvidia.com> > --- > include/linux/mm.h | 48 ++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 46 insertions(+), 2 deletions(-)
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Just one nit below:
> +/* Pages that were pinned via get_user_pages*() should be released via > + * either put_user_page(), or one of the put_user_pages*() routines > + * below. > + */
Multi-line comments usually follow formatting:
/* * Some text here * and more text here... */
Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR
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