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On Fri, Aug 23, 2019 at 03:17:53PM -0700, Ralph Campbell wrote: > Signed-off-by: Ralph Campbell <rcampbell at nvidia.com> > 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 && !(wal...

I have been working on converting Jerome's hmm_dummy driver and self tests into a stand-alone set of tests to be included in tools/testing/selftests/vm and came across these two bug fixes in the process. The tests aren't quite ready to be posted as a patch. I'm posting the fixes now since I thought they shouldn't wait. They should probably have a fixes line but with all the HMM

...alk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(vma=0) Signed-off-by: Ralph Campbell <rcampbell at nvidia.com> --- mm/hmm.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/hmm.c b/mm/hmm.c index fc05c8fe78b4..29371485fe94 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -229,6 +229,9 @@ static int hmm_vma_do_fault(struct mm_walk *walk, unsigned long addr, struct vm_area_struct *vma = walk->vma; vm_fault_t ret; + if (!vma) + goto err; + if (hmm_vma_walk->flags & HMM_FAULT_ALLOW_RETRY) flags |= FAULT_FLAG...

.../* loops on -EBUSY and range->valid */ Prevent this by checking for vma->vm_flags & VM_WRITE before calling handle_mm_fault(). Signed-off-by: Ralph Campbell <rcampbell at nvidia.com> --- mm/hmm.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hmm.c b/mm/hmm.c index 29371485fe94..4882b83aeccb 100644 --- a/mm/hmm.c +++ 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->v...

...Gunthorpe wrote: > On Fri, Aug 23, 2019 at 03:17:53PM -0700, Ralph Campbell wrote: > >> Signed-off-by: Ralph Campbell <rcampbell at nvidia.com> >> 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 && wa...