On 22.10.19 19:12, David Hildenbrand wrote:
Right now, ZONE_DEVICE memory is always set PG_reserved. We want to
change that.
Let's make sure that the logic in the function won't change. Once we no
longer set these pages to reserved, we can rework this function to
perform separate checks for ZONE_DEVICE (split from PG_reserved checks).
Cc: Kees Cook <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Kate Stewart <[email protected]>
Cc: Allison Randal <[email protected]>
Cc: "Isaac J. Manjarres" <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
---
mm/usercopy.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/usercopy.c b/mm/usercopy.c
index 660717a1ea5c..a3ac4be35cde 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -203,14 +203,15 @@ static inline void check_page_span(const void *ptr,
unsigned long n,
* device memory), or CMA. Otherwise, reject since the object spans
* several independently allocated pages.
*/
- is_reserved = PageReserved(page);
+ is_reserved = PageReserved(page) || is_zone_device_page(page);
is_cma = is_migrate_cma_page(page);
if (!is_reserved && !is_cma)
usercopy_abort("spans multiple pages", NULL, to_user, 0, n);
for (ptr += PAGE_SIZE; ptr <= end; ptr += PAGE_SIZE) {
page = virt_to_head_page(ptr);
- if (is_reserved && !PageReserved(page))
+ if (is_reserved && !(PageReserved(page) ||
+ is_zone_device_page(page)))
usercopy_abort("spans Reserved and non-Reserved pages",
NULL, to_user, 0, n);
if (is_cma && !is_migrate_cma_page(page))
@Kees, would it be okay to stop checking against ZONE_DEVICE pages here
or is there a good rationale behind this?
(I would turn this patch into a simple update of the comment if we agree
that we don't care)
--
Thanks,
David / dhildenb
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