[PATCH 02/10] mm/hmm: do not erase snapshot when a range is invalidated

[jglisse]

From: Jérôme Glisse <jgli...@redhat.com>

Users of HMM might be using the snapshot information to do
preparatory step like dma mapping pages to a device before
checking for invalidation through hmm_vma_range_done() so
do not erase that information and assume users will do the
right thing.

Signed-off-by: Jérôme Glisse <jgli...@redhat.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Ralph Campbell <rcampb...@nvidia.com>
Cc: John Hubbard <jhubb...@nvidia.com>
---
 mm/hmm.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/mm/hmm.c b/mm/hmm.c
index b9f384ea15e9..74d69812d6be 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -170,16 +170,10 @@ static int hmm_invalidate_range(struct hmm *hmm, bool 
device,
 
        spin_lock(&hmm->lock);
        list_for_each_entry(range, &hmm->ranges, list) {
-               unsigned long addr, idx, npages;
-
                if (update->end < range->start || update->start >= range->end)
                        continue;
 
                range->valid = false;
-               addr = max(update->start, range->start);
-               idx = (addr - range->start) >> PAGE_SHIFT;
-               npages = (min(range->end, update->end) - addr) >> PAGE_SHIFT;
-               memset(&range->pfns[idx], 0, sizeof(*range->pfns) * npages);
        }
        spin_unlock(&hmm->lock);
 
-- 
2.17.2