mm: page_vma_mapped_walk(): prettify PVMW_MIGRATION block

page_vma_mapped_walk() cleanup: rearrange the !pmd_present() block to
follow the same "return not_found, return not_found, return true"
pattern as the block above it (note: returning not_found there is never
premature, since existence or prior existence of huge pmd guarantees
good alignment).

Link: https://lkml.kernel.org/r/378c8650-1488-2edf-9647-32a53cf2e21@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Wang Yugui <wangyugui@e16-tech.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 8f972b0..261fc92 100644 (file)
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -198,24 +198,22 @@ restart:
                        if (pmd_page(pmde) != page)
                                return not_found(pvmw);
                        return true;
-               } else if (!pmd_present(pmde)) {
-                       if (thp_migration_supported()) {
-                               if (!(pvmw->flags & PVMW_MIGRATION))
-                                       return not_found(pvmw);
-                               if (is_migration_entry(pmd_to_swp_entry(pmde))) {
-                                       swp_entry_t entry = pmd_to_swp_entry(pmde);
+               }
+               if (!pmd_present(pmde)) {
+                       swp_entry_t entry;
 
-                                       if (migration_entry_to_page(entry) != page)
-                                               return not_found(pvmw);
-                                       return true;
-                               }
-                       }
-                       return not_found(pvmw);
-               } else {
-                       /* THP pmd was split under us: handle on pte level */
-                       spin_unlock(pvmw->ptl);
-                       pvmw->ptl = NULL;
+                       if (!thp_migration_supported() ||
+                           !(pvmw->flags & PVMW_MIGRATION))
+                               return not_found(pvmw);
+                       entry = pmd_to_swp_entry(pmde);
+                       if (!is_migration_entry(entry) ||
+                           migration_entry_to_page(entry) != page)
+                               return not_found(pvmw);
+                       return true;
                }
+               /* THP pmd was split under us: handle on pte level */
+               spin_unlock(pvmw->ptl);
+               pvmw->ptl = NULL;
        } else if (!pmd_present(pmde)) {
                /*
                 * If PVMW_SYNC, take and drop THP pmd lock so that we