mm/migrate_device: allow pte_offset_map_lock() to fail

migrate_vma_collect_pmd(): remove the pmd_trans_unstable() handling after
splitting huge zero pmd, and the pmd_none() handling after successfully
splitting huge page: those are now managed inside pte_offset_map_lock(),
and by "goto again" when it fails.

But the skip after unsuccessful split_huge_page() must stay: it avoids an
endless loop.  The skip when pmd_bad()?  Remove that: it will be treated
as a hole rather than a skip once cleared by pte_offset_map_lock(), but
with different timing that would be so anyway; and it's arguably best to
leave the pmd_bad() handling centralized there.

migrate_vma_insert_page(): remove comment on the old pte_offset_map() and
old locking limitations; remove the pmd_trans_unstable() check and just
proceed to pte_offset_map_lock(), aborting when it fails (page has been
charged to memcg, but as in other cases, it's uncharged when freed).

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]>

0 files changed, 0 insertions, 0 deletions