[Xen-devel] [PATCH v2 12/34] vmci: convert put_page() to put_user_page*()

[john.hubbard@xxxxxxxxx]

From: John Hubbard <jhubbard@xxxxxxxxxx>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

Note that this effectively changes the code's behavior in
qp_release_pages(): it now ultimately calls set_page_dirty_lock(),
instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.GB720@xxxxxx

Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
 drivers/misc/vmw_vmci/vmci_context.c    |  2 +-
 drivers/misc/vmw_vmci/vmci_queue_pair.c | 11 ++---------
 2 files changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/vmw_vmci/vmci_context.c 
b/drivers/misc/vmw_vmci/vmci_context.c
index 16695366ec92..9daa52ee63b7 100644
--- a/drivers/misc/vmw_vmci/vmci_context.c
+++ b/drivers/misc/vmw_vmci/vmci_context.c
@@ -587,7 +587,7 @@ void vmci_ctx_unset_notify(struct vmci_ctx *context)
 
        if (notify_page) {
                kunmap(notify_page);
-               put_page(notify_page);
+               put_user_page(notify_page);
        }
 }
 
diff --git a/drivers/misc/vmw_vmci/vmci_queue_pair.c 
b/drivers/misc/vmw_vmci/vmci_queue_pair.c
index 8531ae781195..e5434551d0ef 100644
--- a/drivers/misc/vmw_vmci/vmci_queue_pair.c
+++ b/drivers/misc/vmw_vmci/vmci_queue_pair.c
@@ -626,15 +626,8 @@ static void qp_release_queue_mutex(struct vmci_queue 
*queue)
 static void qp_release_pages(struct page **pages,
                             u64 num_pages, bool dirty)
 {
-       int i;
-
-       for (i = 0; i < num_pages; i++) {
-               if (dirty)
-                       set_page_dirty(pages[i]);
-
-               put_page(pages[i]);
-               pages[i] = NULL;
-       }
+       put_user_pages_dirty_lock(pages, num_pages, dirty);
+       memset(pages, 0, num_pages * sizeof(struct page *));
 }
 
 /*
-- 
2.22.0


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