On Fri, May 22, 2020 at 06:52:34PM -0700, John Hubbard wrote: > On 2020-05-19 13:14, John Hubbard wrote: > > 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 Moritz and FPGA developers, > > Is this OK? And if so, is it going into your git tree? Or should I > send it up through a different tree? (I'm new to the FPGA development > model). I can take it, sorry for sluggish response. Cheers, Moritz > > > thanks, > -- > John Hubbard > NVIDIA > > > > > --- > > > > Hi, > > > > Changes since v1: > > > > Changed the label from "put_pages", to "unpin_pages". > > > > 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 62f924489db5..a31dd3a7e581 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); > > @@ -57,11 +48,11 @@ 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 put_pages; > > + goto unpin_pages; > > } else if (pinned != npages) { > > ret = -EFAULT; > > goto free_pages; > > @@ -71,8 +62,8 @@ static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata, > > 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); > > >
