drm/i915: convert get_user_pages() --> pin_user_pages()

This code was using get_user_pages*(), in a "Case 2" scenario (DMA/RDMA),
using the categorization from [1].  That means that it's time to convert
the get_user_pages*() + put_page() calls to pin_user_pages*() +
unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small part
of fixing a long-standing disconnect between pinning pages, and file
systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Link: http://lkml.kernel.org/r/20200519002124.2025955-5-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
index f80cf6a..33776b3 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
@@ -471,7 +471,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
                                        down_read(&mm->mmap_sem);
                                        locked = 1;
                                }
-                               ret = get_user_pages_remote
+                               ret = pin_user_pages_remote
                                        (work->task, mm,
                                         obj->userptr.ptr + pinned * PAGE_SIZE,
                                         npages - pinned,
@@ -507,7 +507,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
        }
        mutex_unlock(&obj->mm.lock);
 
-       release_pages(pvec, pinned);
+       unpin_user_pages(pvec, pinned);
        kvfree(pvec);
 
        i915_gem_object_put(obj);
@@ -564,6 +564,7 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
        struct sg_table *pages;
        bool active;
        int pinned;
+       unsigned int gup_flags = 0;
 
        /* If userspace should engineer that these pages are replaced in
         * the vma between us binding this page into the GTT and completion
@@ -606,11 +607,14 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
                 *
                 * We may or may not care.
                 */
-               if (pvec) /* defer to worker if malloc fails */
-                       pinned = __get_user_pages_fast(obj->userptr.ptr,
-                                                      num_pages,
-                                                      !i915_gem_object_is_readonly(obj),
-                                                      pvec);
+               if (pvec) {
+                       /* defer to worker if malloc fails */
+                       if (!i915_gem_object_is_readonly(obj))
+                               gup_flags |= FOLL_WRITE;
+                       pinned = pin_user_pages_fast_only(obj->userptr.ptr,
+                                                         num_pages, gup_flags,
+                                                         pvec);
+               }
        }
 
        active = false;
@@ -628,7 +632,7 @@ static int i915_gem_userptr_get_pages(struct drm_i915_gem_object *obj)
                __i915_gem_userptr_set_active(obj, true);
 
        if (IS_ERR(pages))
-               release_pages(pvec, pinned);
+               unpin_user_pages(pvec, pinned);
        kvfree(pvec);
 
        return PTR_ERR_OR_ZERO(pages);
@@ -683,7 +687,7 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
                }
 
                mark_page_accessed(page);
-               put_page(page);
+               unpin_user_page(page);
        }
        obj->mm.dirty = false;