diff options
| author | Peter Xu <peterx@redhat.com> | 2020-08-21 19:49:57 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-09-04 09:25:20 -0700 |
| commit | a308c71bf1e6e19cc2e4ced31853ee0fc7cb439a (patch) | |
| tree | f419a838cdc2f2616adfed4994465738a4167cac /drivers/gpu/drm/i915/gem/i915_gem_userptr.c | |
| parent | 1a0cf26323c80e2f1c58fc04f15686de61bfab0c (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/gpu/drm/i915/gem/i915_gem_userptr.c')
| -rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 8 |
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)) |