[PATCH v3] drm/vmwgfx: Fix race issue calling pin_user_pages

[Dawei Li]

pin_user_pages() is unsafe without protection of mmap_lock,
fix it by calling pin_user_pages_fast().

Fixes: 7a7a933edd6c ("drm/vmwgfx: Introduce VMware mks-guest-stats")
Signed-off-by: Dawei Li <set_pte_at at outlook.com>
---
v1:
https://lore.kernel.org/all/TYCP286MB23235C9A9FCF85C045F95EA7CA4F9@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM/

v1->v2:
Rebased to latest vmwgfx/drm-misc-fixes.

v2->v3
Replace pin_user_pages() with pin_user_pages_fast().
---
 drivers/gpu/drm/vmwgfx/vmwgfx_msg.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
index 089046fa21be..50fa3df0bc0c 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_msg.c
@@ -1085,21 +1085,21 @@ int vmw_mksstat_add_ioctl(struct drm_device *dev, void *data,
 	reset_ppn_array(pdesc->strsPPNs, ARRAY_SIZE(pdesc->strsPPNs));
 
 	/* Pin mksGuestStat user pages and store those in the instance descriptor */
-	nr_pinned_stat = pin_user_pages(arg->stat, num_pages_stat, FOLL_LONGTERM, pages_stat, NULL);
+	nr_pinned_stat = pin_user_pages_fast(arg->stat, num_pages_stat, FOLL_LONGTERM, pages_stat);
 	if (num_pages_stat != nr_pinned_stat)
 		goto err_pin_stat;
 
 	for (i = 0; i < num_pages_stat; ++i)
 		pdesc->statPPNs[i] = page_to_pfn(pages_stat[i]);
 
-	nr_pinned_info = pin_user_pages(arg->info, num_pages_info, FOLL_LONGTERM, pages_info, NULL);
+	nr_pinned_info = pin_user_pages_fast(arg->info, num_pages_info, FOLL_LONGTERM, pages_info);
 	if (num_pages_info != nr_pinned_info)
 		goto err_pin_info;
 
 	for (i = 0; i < num_pages_info; ++i)
 		pdesc->infoPPNs[i] = page_to_pfn(pages_info[i]);
 
-	nr_pinned_strs = pin_user_pages(arg->strs, num_pages_strs, FOLL_LONGTERM, pages_strs, NULL);
+	nr_pinned_strs = pin_user_pages_fast(arg->strs, num_pages_strs, FOLL_LONGTERM, pages_strs);
 	if (num_pages_strs != nr_pinned_strs)
 		goto err_pin_strs;
 
-- 
2.25.1