Re: [PATCH 1/1] infiniband/mm: convert put_page() to put_user_page*()

Ira Weiny
2019-05-23T17:28:02Z

On Thu, May 23, 2019 at 12:25:37AM -0700, john.hubbard@gmail.com wrote:
> From: John Hubbard <jhubbard@nvidia.com>
>
> For infiniband code that retains pages via get_user_pages*(),
> release those pages via the new put_user_page(), or
> put_user_pages*(), instead of put_page()
>
> This is a tiny part of the second step of fixing the problem described
> in [1]. The steps are:
>
> 1) Provide put_user_page*() routines, intended to be used
> for releasing pages that were pinned via get_user_pages*().
>
> 2) Convert all of the call sites for get_user_pages*(), to
> invoke put_user_page*(), instead of put_page(). This involves dozens of
> call sites, and will take some time.
>
> 3) After (2) is complete, use get_user_pages*() and put_user_page*() to
> implement tracking of these pages. This tracking will be separate from
> the existing struct page refcounting.
>
> 4) Use the tracking and identification of these pages, to implement
> special handling (especially in writeback paths) when the pages are
> backed by a filesystem. Again, [1] provides details as to why that is
> desirable.
>
> [1] https://lwn.net/Articles/753027/ : "The Trouble with get_user_pages()"
>
> Cc: Doug Ledford <dledford@redhat.com>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: Mike Marciniszyn <mike.marciniszyn@intel.com>
> Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
> Cc: Christian Benvenuti <benve@cisco.com>
>
> Reviewed-by: Jan Kara <jack@suse.cz>
> Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
> Acked-by: Jason Gunthorpe <jgg@mellanox.com>
> Tested-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
> drivers/infiniband/core/umem.c | 7 ++++---
> drivers/infiniband/core/umem_odp.c | 10 +++++-----
> drivers/infiniband/hw/hfi1/user_pages.c | 11 ++++-------
> drivers/infiniband/hw/mthca/mthca_memfree.c | 6 +++---
> drivers/infiniband/hw/qib/qib_user_pages.c | 11 ++++-------
> drivers/infiniband/hw/qib/qib_user_sdma.c | 6 +++---
> drivers/infiniband/hw/usnic/usnic_uiom.c | 7 ++++---
> 7 files changed, 27 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> index e7ea819fcb11..673f0d240b3e 100644
> --- a/drivers/infiniband/core/umem.c
> +++ b/drivers/infiniband/core/umem.c
> @@ -54,9 +54,10 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
>
> for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
> page = sg_page_iter_page(&sg_iter);
> - if (!PageDirty(page) && umem->writable && dirty)
> - set_page_dirty_lock(page);
> - put_page(page);
> + if (umem->writable && dirty)
> + put_user_pages_dirty_lock(&page, 1);
> + else
> + put_user_page(page);
> }
>
> sg_free_table(&umem->sg_head);
> diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
> index f962b5bbfa40..17e46df3990a 100644
> --- a/drivers/infiniband/core/umem_odp.c
> +++ b/drivers/infiniband/core/umem_odp.c
> @@ -487,7 +487,7 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
> * The function returns -EFAULT if the DMA mapping operation fails. It returns
> * -EAGAIN if a concurrent invalidation prevents us from updating the page.
> *
> - * The page is released via put_page even if the operation failed. For
> + * The page is released via put_user_page even if the operation failed. For
> * on-demand pinning, the page is released whenever it isn't stored in the
> * umem.
> */
> @@ -536,7 +536,7 @@ static int ib_umem_odp_map_dma_single_page(
> }
>
> out:
> - put_page(page);
> + put_user_page(page);
>
> if (remove_existing_mapping) {
> ib_umem_notifier_start_account(umem_odp);
> @@ -659,7 +659,7 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> ret = -EFAULT;
> break;
> }
> - put_page(local_page_list[j]);
> + put_user_page(local_page_list[j]);
> continue;
> }
>
> @@ -686,8 +686,8 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> * ib_umem_odp_map_dma_single_page().
> */
> if (npages - (j + 1) > 0)
> - release_pages(&local_page_list[j+1],
> - npages - (j + 1));
> + put_user_pages(&local_page_list[j+1],
> + npages - (j + 1));

I don't know if we discussed this before but it looks like the use of
release_pages() was not entirely correct (or at least not necessary) here. So
I think this is ok.

As for testing, I have been running with this patch for a while but I don't
have ODP hardware so that testing would not cover this code path. So you can
add my:

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> break;
> }
> }
> diff --git a/drivers/infiniband/hw/hfi1/user_pages.c b/drivers/infiniband/hw/hfi1/user_pages.c
> index 02eee8eff1db..b89a9b9aef7a 100644
> --- a/drivers/infiniband/hw/hfi1/user_pages.c
> +++ b/drivers/infiniband/hw/hfi1/user_pages.c
> @@ -118,13 +118,10 @@ int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t np
> void hfi1_release_user_pages(struct mm_struct *mm, struct page **p,
> size_t npages, bool dirty)
> {
> - size_t i;
> -
> - for (i = 0; i < npages; i++) {
> - if (dirty)
> - set_page_dirty_lock(p[i]);
> - put_page(p[i]);
> - }
> + if (dirty)
> + put_user_pages_dirty_lock(p, npages);
> + else
> + put_user_pages(p, npages);
>
> if (mm) { /* during close after signal, mm can be NULL */
> atomic64_sub(npages, &mm->pinned_vm);
> diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
> index 8ff0e90d7564..edccfd6e178f 100644
> --- a/drivers/infiniband/hw/mthca/mthca_memfree.c
> +++ b/drivers/infiniband/hw/mthca/mthca_memfree.c
> @@ -482,7 +482,7 @@ int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
>
> ret = pci_map_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
> if (ret < 0) {
> - put_page(pages[0]);
> + put_user_page(pages[0]);
> goto out;
> }
>
> @@ -490,7 +490,7 @@ int mthca_map_user_db(struct mthca_dev *dev, struct mthca_uar *uar,
> mthca_uarc_virt(dev, uar, i));
> if (ret) {
> pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
> - put_page(sg_page(&db_tab->page[i].mem));
> + put_user_page(sg_page(&db_tab->page[i].mem));
> goto out;
> }
>
> @@ -556,7 +556,7 @@ void mthca_cleanup_user_db_tab(struct mthca_dev *dev, struct mthca_uar *uar,
> if (db_tab->page[i].uvirt) {
> mthca_UNMAP_ICM(dev, mthca_uarc_virt(dev, uar, i), 1);
> pci_unmap_sg(dev->pdev, &db_tab->page[i].mem, 1, PCI_DMA_TODEVICE);
> - put_page(sg_page(&db_tab->page[i].mem));
> + put_user_page(sg_page(&db_tab->page[i].mem));
> }
> }
>
> diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c
> index f712fb7fa82f..bfbfbb7e0ff4 100644
> --- a/drivers/infiniband/hw/qib/qib_user_pages.c
> +++ b/drivers/infiniband/hw/qib/qib_user_pages.c
> @@ -40,13 +40,10 @@
> static void __qib_release_user_pages(struct page **p, size_t num_pages,
> int dirty)
> {
> - size_t i;
> -
> - for (i = 0; i < num_pages; i++) {
> - if (dirty)
> - set_page_dirty_lock(p[i]);
> - put_page(p[i]);
> - }
> + if (dirty)
> + put_user_pages_dirty_lock(p, num_pages);
> + else
> + put_user_pages(p, num_pages);
> }
>
> /**
> diff --git a/drivers/infiniband/hw/qib/qib_user_sdma.c b/drivers/infiniband/hw/qib/qib_user_sdma.c
> index 0c204776263f..ac5bdb02144f 100644
> --- a/drivers/infiniband/hw/qib/qib_user_sdma.c
> +++ b/drivers/infiniband/hw/qib/qib_user_sdma.c
> @@ -317,7 +317,7 @@ static int qib_user_sdma_page_to_frags(const struct qib_devdata *dd,
> * the caller can ignore this page.
> */
> if (put) {
> - put_page(page);
> + put_user_page(page);
> } else {
> /* coalesce case */
> kunmap(page);
> @@ -631,7 +631,7 @@ static void qib_user_sdma_free_pkt_frag(struct device *dev,
> kunmap(pkt->addr[i].page);
>
> if (pkt->addr[i].put_page)
> - put_page(pkt->addr[i].page);
> + put_user_page(pkt->addr[i].page);
> else
> __free_page(pkt->addr[i].page);
> } else if (pkt->addr[i].kvaddr) {
> @@ -706,7 +706,7 @@ static int qib_user_sdma_pin_pages(const struct qib_devdata *dd,
> /* if error, return all pages not managed by pkt */
> free_pages:
> while (i < j)
> - put_page(pages[i++]);
> + put_user_page(pages[i++]);
>
> done:
> return ret;
> diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
> index e312f522a66d..0b0237d41613 100644
> --- a/drivers/infiniband/hw/usnic/usnic_uiom.c
> +++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
> @@ -75,9 +75,10 @@ static void usnic_uiom_put_pages(struct list_head *chunk_list, int dirty)
> for_each_sg(chunk->page_list, sg, chunk->nents, i) {
> page = sg_page(sg);
> pa = sg_phys(sg);
> - if (!PageDirty(page) && dirty)
> - set_page_dirty_lock(page);
> - put_page(page);
> + if (dirty)
> + put_user_pages_dirty_lock(&page, 1);
> + else
> + put_user_page(page);
> usnic_dbg("pa: %pa\n", &pa);
> }
> kfree(chunk);
> --
> 2.21.0
>