[PATCH 2/2] infiniband/mm: convert put_page() to put_user_page*()

[john . hubbard]

From: John Hubbard <jhubbard@xxxxxxxxxx>

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@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
Cc: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>
Cc: Christian Benvenuti <benve@xxxxxxxxx>

Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxx>
Acked-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
 drivers/infiniband/core/umem.c              |  7 ++++---
 drivers/infiniband/core/umem_odp.c          |  2 +-
 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, 23 insertions(+), 27 deletions(-)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index c6144df47ea4..c2898bc7b3b2 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -58,9 +58,10 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
 	for_each_sg(umem->sg_head.sgl, sg, umem->npages, i) {
 
 		page = sg_page(sg);
-		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 acb882f279cb..d32757c1f77e 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -663,7 +663,7 @@ 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;
 			}
 
diff --git a/drivers/infiniband/hw/hfi1/user_pages.c b/drivers/infiniband/hw/hfi1/user_pages.c
index e341e6dcc388..99ccc0483711 100644
--- a/drivers/infiniband/hw/hfi1/user_pages.c
+++ b/drivers/infiniband/hw/hfi1/user_pages.c
@@ -121,13 +121,10 @@ 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 */
 		down_write(&mm->mmap_sem);
diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
index 112d2f38e0de..99108f3dcf01 100644
--- a/drivers/infiniband/hw/mthca/mthca_memfree.c
+++ b/drivers/infiniband/hw/mthca/mthca_memfree.c
@@ -481,7 +481,7 @@ 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;
 	}
 
@@ -489,7 +489,7 @@ 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;
 	}
 
@@ -555,7 +555,7 @@ 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 16543d5e80c3..1a5c64c8695f 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 31c523b2a9f5..a1a1ec4adffc 100644
--- a/drivers/infiniband/hw/qib/qib_user_sdma.c
+++ b/drivers/infiniband/hw/qib/qib_user_sdma.c
@@ -320,7 +320,7 @@ 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);
@@ -634,7 +634,7 @@ 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) {
@@ -709,7 +709,7 @@ 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 49275a548751..2ef8d31dc838 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -77,9 +77,10 @@ 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);
-- 
2.20.1