mm/hmm: retry if pte_offset_map() fails

hmm_vma_walk_pmd() is called through mm_walk, but already has a goto again
loop of its own, so take part in that if pte_offset_map() fails.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hugh Dickins <[email protected]>
Reviewed-by: Alistair Popple <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Qi Zheng <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Steven Price <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Thomas Hellström <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yu Zhao <[email protected]>
Cc: Zack Rusin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/mm/hmm.c b/mm/hmm.c
index e23043345615..b1a9159d7c92 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -381,6 +381,8 @@ again:
 	}
 
 	ptep = pte_offset_map(pmdp, addr);
+	if (!ptep)
+		goto again;
 	for (; addr < end; addr += PAGE_SIZE, ptep++, hmm_pfns++) {
 		int r;