On Wed 16-11-16 14:32:48, Kirill A. Shutemov wrote:
> On Wed, Nov 16, 2016 at 12:05:05PM +0100, Jan Kara wrote:
> > On Wed 16-11-16 00:55:31, Kirill A. Shutemov wrote:
> > > On Fri, Nov 04, 2016 at 05:24:58AM +0100, Jan Kara wrote:
> > > > Every single user of vmf->virtual_address typed that entry to unsigned
> > > > long before doing anything with it so the type of virtual_address does
> > > > not really provide us any additional safety. Just use masked
> > > > vmf->address which already has the appropriate type.
> > > >
> > > > Signed-off-by: Jan Kara <jack@xxxxxxx>
> > > > ---
> > > > arch/powerpc/platforms/cell/spufs/file.c | 4 ++--
> > > > arch/x86/entry/vdso/vma.c | 4 ++--
> > > > drivers/char/agp/alpha-agp.c | 2 +-
> > > > drivers/char/mspec.c | 2 +-
> > > > drivers/dax/dax.c | 2 +-
> > > > drivers/gpu/drm/armada/armada_gem.c | 2 +-
> > > > drivers/gpu/drm/drm_vm.c | 11 ++++++-----
> > > > drivers/gpu/drm/etnaviv/etnaviv_gem.c | 7 +++----
> > > > drivers/gpu/drm/exynos/exynos_drm_gem.c | 6 +++---
> > > > drivers/gpu/drm/gma500/framebuffer.c | 2 +-
> > > > drivers/gpu/drm/gma500/gem.c | 5 ++---
> > > > drivers/gpu/drm/i915/i915_gem.c | 2 +-
> > > > drivers/gpu/drm/msm/msm_gem.c | 7 +++----
> > > > drivers/gpu/drm/omapdrm/omap_gem.c | 20 +++++++++-----------
> > > > drivers/gpu/drm/tegra/gem.c | 4 ++--
> > > > drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 +-
> > > > drivers/gpu/drm/udl/udl_gem.c | 5 ++---
> > > > drivers/gpu/drm/vgem/vgem_drv.c | 2 +-
> > > > drivers/media/v4l2-core/videobuf-dma-sg.c | 5 ++---
> > > > drivers/misc/cxl/context.c | 2 +-
> > > > drivers/misc/sgi-gru/grumain.c | 2 +-
> > > > drivers/staging/android/ion/ion.c | 2 +-
> > > > drivers/staging/lustre/lustre/llite/vvp_io.c | 9 ++++++---
> > > > drivers/xen/privcmd.c | 2 +-
> > > > fs/dax.c | 4 ++--
> > > > include/linux/mm.h | 2 --
> > > > mm/memory.c | 7 +++----
> > > > 27 files changed, 59 insertions(+), 65 deletions(-)
> > > >
> > > > diff --git a/arch/powerpc/platforms/cell/spufs/file.c b/arch/powerpc/platforms/cell/spufs/file.c
> > > > index 06254467e4dd..e8a31fffcdda 100644
> > > > --- a/arch/powerpc/platforms/cell/spufs/file.c
> > > > +++ b/arch/powerpc/platforms/cell/spufs/file.c
> > > > @@ -236,7 +236,7 @@ static int
> > > > spufs_mem_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> > > > {
> > > > struct spu_context *ctx = vma->vm_file->private_data;
> > > > - unsigned long address = (unsigned long)vmf->virtual_address;
> > > > + unsigned long address = vmf->address & PAGE_MASK;
> > >
> > > These "& PAGE_MASK" everewhere look unnecesary. I don't think we ever
> > > need sub-page address, do we?
> >
> > Usually not AFAICT but I was not really sure in some cases (e.g. is
> > vm_insert_pfn() and friends really safe to call with unaligned address) so
> > I've decided to do a simple search-and-replace for such a wide-scale patch.
> > Later we can remove unnecessary masking from places where we are sure it is
> > not needed.
>
> I think it should be fine just to zero out ~PAGE_MASK bits of the address
> on entrance into handle_mm_fault() or where vmf is initialized.
OK, I wasn't really sure whether something in mm does not rely on low bits
being accurate. But if you also don't think anything relies on those bits,
I can try it we'll see if something breaks :)
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
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