include/linux/migrate_mode.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef MIGRATE_MODE_H_INCLUDED
   3 #define MIGRATE_MODE_H_INCLUDED
   4 /*
   5  * MIGRATE_ASYNC means never block
   6  * MIGRATE_SYNC_LIGHT in the current implementation means to allow blocking
   7  *      on most operations but not ->writepage as the potential stall time
   8  *      is too significant
   9  * MIGRATE_SYNC will block when migrating pages
  10  * MIGRATE_SYNC_NO_COPY will block when migrating pages but will not copy pages
  11  *      with the CPU. Instead, page copy happens outside the migratepage()
  12  *      callback and is likely using a DMA engine. See migrate_vma() and HMM
  13  *      (mm/hmm.c) for users of this mode.
  14  */
  15 enum migrate_mode {
  16         MIGRATE_ASYNC,
  17         MIGRATE_SYNC_LIGHT,
  18         MIGRATE_SYNC,
  19         MIGRATE_SYNC_NO_COPY,
  20 };
  21
  22 #endif          /* MIGRATE_MODE_H_INCLUDED */