> -----Original Message----- > From: John Hubbard <jhubbard@xxxxxxxxxx> > Sent: Tuesday, May 26, 2020 6:18 AM > To: LKML <linux-kernel@xxxxxxxxxxxxxxx> > Cc: John Hubbard <jhubbard@xxxxxxxxxx>; Xu, Yilun <yilun.xu@xxxxxxxxx>; > Wu, Hao <hao.wu@xxxxxxxxx>; Moritz Fischer <mdf@xxxxxxxxxx>; linux- > fpga@xxxxxxxxxxxxxxx > Subject: [PATCH v3] fpga: dfl: afu: 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: Xu Yilun <yilun.xu@xxxxxxxxx> > Cc: Wu Hao <hao.wu@xxxxxxxxx> > Cc: Moritz Fischer <mdf@xxxxxxxxxx> > Cc: linux-fpga@xxxxxxxxxxxxxxx > Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx> > --- > > 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 > <Souptick Joarder>") Thanks a lot! Acked-by: Wu Hao <hao.wu@xxxxxxxxx> Thanks Hao > > 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- > region.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 @@ > > #include "dfl-afu.h" > > -static void put_all_pages(struct page **pages, int npages) > -{ > - int i; > - > - for (i = 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 = dfl_fpga_pdata_get_private(pdata); > @@ -57,22 +48,22 @@ static int afu_dma_pin_pages(struct > dfl_feature_platform_data *pdata, > goto unlock_vm; > } > > - pinned = get_user_pages_fast(region->user_addr, npages, > FOLL_WRITE, > + pinned = pin_user_pages_fast(region->user_addr, npages, > FOLL_WRITE, > region->pages); > if (pinned < 0) { > ret = pinned; > goto free_pages; > } else if (pinned != npages) { > ret = -EFAULT; > - goto put_pages; > + goto unpin_pages; > } > > dev_dbg(dev, "%d pages pinned\n", pinned); > > return 0; > > -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_platform_data *pdata, > long npages = region->length >> PAGE_SHIFT; > struct device *dev = &pdata->dev->dev; > > - put_all_pages(region->pages, npages); > + unpin_user_pages(region->pages, npages); > kfree(region->pages); > account_locked_vm(current->mm, npages, false); > > -- > 2.26.2
