From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:7188 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388054AbgEYWR4 (ORCPT ); Mon, 25 May 2020 18:17:56 -0400 From: John Hubbard Subject: [PATCH v3] fpga: dfl: afu: convert get_user_pages() --> pin_user_pages() Date: Mon, 25 May 2020 15:17:54 -0700 Message-ID: <20200525221754.433023-1-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain Sender: linux-fpga-owner@vger.kernel.org List-Id: linux-fpga@vger.kernel.org To: LKML Cc: John Hubbard , Xu Yilun , Wu Hao , Moritz Fischer , linux-fpga@vger.kernel.org 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: Xu Yilun Cc: Wu Hao Cc: Moritz Fischer Cc: linux-fpga@vger.kernel.org Signed-off-by: John Hubbard --- Hi, This is the same logical change as in v2, but it is applied to char-misc-next, in order to avoid a merge problem with Souptick's commit c9d7e3da1f3c ("fpga: dfl: afu: Corrected error handling levels ") thanks, John Hubbard NVIDIA drivers/fpga/dfl-afu-dma-region.c | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) diff --git a/drivers/fpga/dfl-afu-dma-region.c b/drivers/fpga/dfl-afu-dma-r= egion.c index 5942343a5d6e..0b817b722920 100644 --- a/drivers/fpga/dfl-afu-dma-region.c +++ b/drivers/fpga/dfl-afu-dma-region.c @@ -16,15 +16,6 @@ =20 #include "dfl-afu.h" =20 -static void put_all_pages(struct page **pages, int npages) -{ - int i; - - for (i =3D 0; i < npages; i++) - if (pages[i]) - put_page(pages[i]); -} - void afu_dma_region_init(struct dfl_feature_platform_data *pdata) { struct dfl_afu *afu =3D dfl_fpga_pdata_get_private(pdata); @@ -57,22 +48,22 @@ static int afu_dma_pin_pages(struct dfl_feature_platfor= m_data *pdata, goto unlock_vm; } =20 - pinned =3D get_user_pages_fast(region->user_addr, npages, FOLL_WRITE, + pinned =3D pin_user_pages_fast(region->user_addr, npages, FOLL_WRITE, region->pages); if (pinned < 0) { ret =3D pinned; goto free_pages; } else if (pinned !=3D npages) { ret =3D -EFAULT; - goto put_pages; + goto unpin_pages; } =20 dev_dbg(dev, "%d pages pinned\n", pinned); =20 return 0; =20 -put_pages: - put_all_pages(region->pages, pinned); +unpin_pages: + unpin_user_pages(region->pages, pinned); free_pages: kfree(region->pages); unlock_vm: @@ -94,7 +85,7 @@ static void afu_dma_unpin_pages(struct dfl_feature_platfo= rm_data *pdata, long npages =3D region->length >> PAGE_SHIFT; struct device *dev =3D &pdata->dev->dev; =20 - put_all_pages(region->pages, npages); + unpin_user_pages(region->pages, npages); kfree(region->pages); account_locked_vm(current->mm, npages, false); =20 --=20 2.26.2