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mm/hmm: do not erase snapshot when a range is invalidated 

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.

Link: http://lkml.kernel.org/r/20190403193318.16478-4-jglisse@redhat.com
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jérôme Glisse 2019-05-13 17:19:52 -07:00 committed by Linus Torvalds
parent 704f3f2cf6
commit 9f454612f6
1 changed files with 0 additions and 6 deletions
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6
mm/hmm.c
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@ -174,16 +174,10 @@ 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);