rds: convert get_user_pages() --> pin_user_pages()
This code was using get_user_pages_fast(), in a "Case 2" scenario (DMA/RDMA), using the categorization from [1]. That means that it's time to convert the get_user_pages_fast() + put_page() calls to pin_user_pages_fast() + unpin_user_pages() calls. There is some helpful background in [2]: basically, this is a small part of fixing a long-standing disconnect between pinning pages, and file systems' use of those pages. [1] Documentation/core-api/pin_user_pages.rst [2] "Explicit pinning of user-space pages": https://lwn.net/Articles/807108/ Cc: David S. Miller <davem@davemloft.net> Cc: Jakub Kicinski <kuba@kernel.org> Cc: netdev@vger.kernel.org Cc: linux-rdma@vger.kernel.org Cc: rds-devel@oss.oracle.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -162,7 +162,6 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
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struct rds_info_lengths lens;
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unsigned long nr_pages = 0;
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unsigned long start;
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unsigned long i;
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rds_info_func func;
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struct page **pages = NULL;
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int ret;
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@ -193,7 +192,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval,
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ret = -ENOMEM;
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goto out;
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}
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ret = get_user_pages_fast(start, nr_pages, FOLL_WRITE, pages);
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ret = pin_user_pages_fast(start, nr_pages, FOLL_WRITE, pages);
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if (ret != nr_pages) {
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if (ret > 0)
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nr_pages = ret;
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@ -235,8 +234,7 @@ call_func:
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ret = -EFAULT;
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out:
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for (i = 0; pages && i < nr_pages; i++)
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put_page(pages[i]);
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unpin_user_pages(pages, nr_pages);
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kfree(pages);
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return ret;
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