From: Jérôme Glisse <[email protected]>

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

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

Changes from Jérôme's original patch:

* Changed a WARN_ON to a BUG_ON.

Signed-off-by: Jérôme Glisse <[email protected]>
Signed-off-by: John Hubbard <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Jan Kara <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Johannes Thumshirn <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Ming Lei <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Boaz Harrosh <[email protected]>
Cc: Miklos Szeredi <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Stefan Hajnoczi <[email protected]>
---
 drivers/vhost/scsi.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index a9caf1bc3c3e..282565ab5e3f 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -329,11 +329,11 @@ static void vhost_scsi_release_cmd(struct se_cmd *se_cmd)
 
        if (tv_cmd->tvc_sgl_count) {
                for (i = 0; i < tv_cmd->tvc_sgl_count; i++)
-                       put_page(sg_page(&tv_cmd->tvc_sgl[i]));
+                       put_user_page(sg_page(&tv_cmd->tvc_sgl[i]));
        }
        if (tv_cmd->tvc_prot_sgl_count) {
                for (i = 0; i < tv_cmd->tvc_prot_sgl_count; i++)
-                       put_page(sg_page(&tv_cmd->tvc_prot_sgl[i]));
+                       put_user_page(sg_page(&tv_cmd->tvc_prot_sgl[i]));
        }
 
        vhost_scsi_put_inflight(tv_cmd->inflight);
@@ -630,6 +630,13 @@ vhost_scsi_map_to_sgl(struct vhost_scsi_cmd *cmd,
        size_t offset;
        unsigned int npages = 0;
 
+       /*
+        * Here in all cases we should have an IOVEC which use GUP. If that is
+        * not the case then we will wrongly call put_user_page() and the page
+        * refcount will go wrong (this is in vhost_scsi_release_cmd())
+        */
+       WARN_ON(!iov_iter_get_pages_use_gup(iter));
+
        bytes = iov_iter_get_pages(iter, pages, LONG_MAX,
                                VHOST_SCSI_PREALLOC_UPAGES, &offset);
        /* No pages were pinned */
@@ -681,7 +688,7 @@ vhost_scsi_iov_to_sgl(struct vhost_scsi_cmd *cmd, bool 
write,
                        while (p < sg) {
                                struct page *page = sg_page(p++);
                                if (page)
-                                       put_page(page);
+                                       put_user_page(page);
                        }
                        return ret;
                }
-- 
2.22.0

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