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-rw-r--r--mm/migrate.c44
1 files changed, 24 insertions, 20 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 5ca5842df5db..5795cb82e27c 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1328,34 +1328,38 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
goto put_anon;
if (page_mapped(hpage)) {
- /*
- * try_to_unmap could potentially call huge_pmd_unshare.
- * Because of this, take semaphore in write mode here and
- * set TTU_RMAP_LOCKED to let lower levels know we have
- * taken the lock.
- */
- mapping = hugetlb_page_mapping_lock_write(hpage);
- if (unlikely(!mapping))
- goto unlock_put_anon;
+ bool mapping_locked = false;
+ enum ttu_flags ttu = TTU_MIGRATION|TTU_IGNORE_MLOCK|
+ TTU_IGNORE_ACCESS;
+
+ if (!PageAnon(hpage)) {
+ /*
+ * In shared mappings, try_to_unmap could potentially
+ * call huge_pmd_unshare. Because of this, take
+ * semaphore in write mode here and set TTU_RMAP_LOCKED
+ * to let lower levels know we have taken the lock.
+ */
+ mapping = hugetlb_page_mapping_lock_write(hpage);
+ if (unlikely(!mapping))
+ goto unlock_put_anon;
+
+ mapping_locked = true;
+ ttu |= TTU_RMAP_LOCKED;
+ }
- try_to_unmap(hpage,
- TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS|
- TTU_RMAP_LOCKED);
+ try_to_unmap(hpage, ttu);
page_was_mapped = 1;
- /*
- * Leave mapping locked until after subsequent call to
- * remove_migration_ptes()
- */
+
+ if (mapping_locked)
+ i_mmap_unlock_write(mapping);
}
if (!page_mapped(hpage))
rc = move_to_new_page(new_hpage, hpage, mode);
- if (page_was_mapped) {
+ if (page_was_mapped)
remove_migration_ptes(hpage,
- rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, true);
- i_mmap_unlock_write(mapping);
- }
+ rc == MIGRATEPAGE_SUCCESS ? new_hpage : hpage, false);
unlock_put_anon:
unlock_page(new_hpage);