On Tue, Aug 27, 2019 at 01:16:13PM -0700, Ralph Campbell wrote: > > On 8/27/19 11:41 AM, Jason Gunthorpe wrote: > > On Fri, Aug 23, 2019 at 03:17:53PM -0700, Ralph Campbell wrote: > > > > > Signed-off-by: Ralph Campbell <rcampbell@xxxxxxxxxx> > > > mm/hmm.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/mm/hmm.c b/mm/hmm.c > > > index 29371485fe94..4882b83aeccb 100644 > > > +++ b/mm/hmm.c > > > @@ -292,6 +292,9 @@ static int hmm_vma_walk_hole_(unsigned long addr, unsigned long end, > > > hmm_vma_walk->last = addr; > > > i = (addr - range->start) >> PAGE_SHIFT; > > > + if (write_fault && walk->vma && !(walk->vma->vm_flags & VM_WRITE)) > > > + return -EPERM; > > > > Can walk->vma be NULL here? hmm_vma_do_fault() touches it > > unconditionally. > > > > Jason > > > walk->vma can be NULL. hmm_vma_do_fault() no longer touches it > unconditionally, that is what the preceding patch fixes. > I suppose I could change hmm_vma_walk_hole_() to check for NULL > and fill in the pfns[] array, I just chose to handle it in > hmm_vma_do_fault(). Okay, yes maybe long term it would be clearer to do the vma null check closer to the start of the callback, but this is a good enough bug fix Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx> Jason
