summaryrefslogtreecommitdiff
path: root/drivers
diff options
context:
space:
mode:
authorPeter Xu <peterx@redhat.com>2020-08-21 19:49:57 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2020-09-04 09:25:20 -0700
commita308c71bf1e6e19cc2e4ced31853ee0fc7cb439a (patch)
treef419a838cdc2f2616adfed4994465738a4167cac /drivers
parent1a0cf26323c80e2f1c58fc04f15686de61bfab0c (diff)
mm/gup: Remove enfornced COW mechanism
With the more strict (but greatly simplified) page reuse logic in do_wp_page(), we can safely go back to the world where cow is not enforced with writes. This essentially reverts commit 17839856fd58 ("gup: document and work around 'COW can break either way' issue"). There are some context differences due to some changes later on around it: 2170ecfa7688 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03) 376a34efa4ee ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03) Some lines moved back and forth with those, but this revert patch should have striped out and covered all the enforced cow bits anyways. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/i915/gem/i915_gem_userptr.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index c31a6744daee..853184db8e83 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -599,14 +599,6 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
GFP_KERNEL |
__GFP_NORETRY |
__GFP_NOWARN);
- /*
- * Using __get_user_pages_fast() with a read-only
- * access is questionable. A read-only page may be
- * COW-broken, and then this might end up giving
- * the wrong side of the COW..
- *
- * We may or may not care.
- */
if (pvec) {
/* defer to worker if malloc fails */
if (!i915_gem_object_is_readonly(obj))