This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + 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: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
Hi,
Changes since v1: rebased onto Linux-5.8-rc2.
thanks,
John Hubbard
drivers/vfio/vfio_iommu_spapr_tce.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 16b3adc508db..fe888b5dcc00 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -383,7 +383,7 @@ static void tce_iommu_unuse_page(struct tce_container *container,
struct page *page;
page = pfn_to_page(hpa >> PAGE_SHIFT);
- put_page(page);
+ unpin_user_page(page);
}
static int tce_iommu_prereg_ua_to_hpa(struct tce_container *container,
@@ -486,7 +486,7 @@ static int tce_iommu_use_page(unsigned long tce, unsigned long *hpa)
struct page *page = NULL;
enum dma_data_direction direction = iommu_tce_direction(tce);
- if (get_user_pages_fast(tce & PAGE_MASK, 1,
+ if (pin_user_pages_fast(tce & PAGE_MASK, 1,
direction != DMA_TO_DEVICE ? FOLL_WRITE : 0,
&page) != 1)
return -EFAULT;
--
2.27.0
