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    Subject[PATCH 06/34] drm/i915: convert put_page() to put_user_page*()
    Date
    From: John Hubbard <jhubbard@nvidia.com>

    For pages that were retained via get_user_pages*(), release those pages
    via the new put_user_page*() routines, instead of via put_page() or
    release_pages().

    This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
    ("mm: introduce put_user_page*(), placeholder versions").

    Note that this effectively changes the code's behavior in
    i915_gem_userptr_put_pages(): it now calls set_page_dirty_lock(),
    instead of set_page_dirty(). This is probably more accurate.

    As Christophe Hellwig put it, "set_page_dirty() is only safe if we are
    dealing with a file backed page where we have reference on the inode it
    hangs off." [1]

    [1] https://lore.kernel.org/r/20190723153640.GB720@lst.de

    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: intel-gfx@lists.freedesktop.org
    Cc: dri-devel@lists.freedesktop.org
    Signed-off-by: John Hubbard <jhubbard@nvidia.com>
    ---
    drivers/gpu/drm/i915/gem/i915_gem_userptr.c | 9 +++------
    1 file changed, 3 insertions(+), 6 deletions(-)

    diff --git a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
    index 528b61678334..c18008d3cc2a 100644
    --- a/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
    +++ b/drivers/gpu/drm/i915/gem/i915_gem_userptr.c
    @@ -527,7 +527,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
    }
    mutex_unlock(&obj->mm.lock);

    - release_pages(pvec, pinned);
    + put_user_pages(pvec, pinned);
    kvfree(pvec);

    i915_gem_object_put(obj);
    @@ -640,7 +640,7 @@ 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);
    + put_user_pages(pvec, pinned);
    kvfree(pvec);

    return PTR_ERR_OR_ZERO(pages);
    @@ -663,11 +663,8 @@ i915_gem_userptr_put_pages(struct drm_i915_gem_object *obj,
    i915_gem_gtt_finish_pages(obj, pages);

    for_each_sgt_page(page, sgt_iter, pages) {
    - if (obj->mm.dirty)
    - set_page_dirty(page);
    -
    mark_page_accessed(page);
    - put_page(page);
    + put_user_pages_dirty_lock(&page, 1, obj->mm.dirty);
    }
    obj->mm.dirty = false;

    --
    2.22.0
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