On 17/08/2023 12:41, Hans Verkuil wrote: > The WARN_ONCE was issued also in cases that had nothing to do with VM_IO > (e.g. if the start address was just a random value and uaccess fails with > -EFAULT). > > There are no reports of WARN_ONCE being issued for actual VM_IO cases, so > just drop it and instead add a note to the comment before the function. > > Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx> I forgot to add: Reported-by: Yikebaer Aizezi <yikebaer61@xxxxxxxxx> > --- > diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/media/common/videobuf2/frame_vector.c > index 0f430ddc1f67..fd87747be9b1 100644 > --- a/drivers/media/common/videobuf2/frame_vector.c > +++ b/drivers/media/common/videobuf2/frame_vector.c > @@ -31,6 +31,10 @@ > * different type underlying the specified range of virtual addresses. > * When the function isn't able to map a single page, it returns error. > * > + * Note that get_vaddr_frames() cannot follow VM_IO mappings. It used > + * to be able to do that, but that could (racily) return non-refcounted > + * pfns. > + * > * This function takes care of grabbing mmap_lock as necessary. > */ > int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, > @@ -59,8 +63,6 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, > if (likely(ret > 0)) > return ret; > > - /* This used to (racily) return non-refcounted pfns. Let people know */ > - WARN_ONCE(1, "get_vaddr_frames() cannot follow VM_IO mapping"); > vec->nr_frames = 0; > return ret ? ret : -EFAULT; > } >
