Commit 2916ecc0f9d4 ("mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY")
introduce a new MIGRATE_SYNC_NO_COPY mode to allow to offload the copy to
a device DMA engine, which is only used __migrate_device_pages() to decide
whether or not copy the old page, and the MIGRATE_SYNC_NO_COPY mode only
set in hmm, as the MIGRATE_SYNC_NO_COPY set is removed by previous cleanup,
it seems that we could remove the unnecessary MIGRATE_SYNC_NO_COPY.
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
fs/aio.c | 12 +-----------
fs/hugetlbfs/inode.c | 5 +----
include/linux/migrate_mode.h | 5 -----
mm/balloon_compaction.c | 8 --------
mm/migrate.c | 8 +-------
mm/zsmalloc.c | 8 --------
6 files changed, 3 insertions(+), 43 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index 6ed5507cd330..dc7a10f2a6e2 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -410,17 +410,7 @@ static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
struct kioctx *ctx;
unsigned long flags;
pgoff_t idx;
- int rc;
-
- /*
- * We cannot support the _NO_COPY case here, because copy needs to
- * happen under the ctx->completion_lock. That does not work with the
- * migration workflow of MIGRATE_SYNC_NO_COPY.
- */
- if (mode == MIGRATE_SYNC_NO_COPY)
- return -EINVAL;
-
- rc = 0;
+ int rc = 0;
/* mapping->i_private_lock here protects against the kioctx teardown. */
spin_lock(&mapping->i_private_lock);
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 412f295acebe..6df794ed4066 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -1128,10 +1128,7 @@ static int hugetlbfs_migrate_folio(struct address_space *mapping,
hugetlb_set_folio_subpool(src, NULL);
}
- if (mode != MIGRATE_SYNC_NO_COPY)
- folio_migrate_copy(dst, src);
- else
- folio_migrate_flags(dst, src);
+ folio_migrate_copy(dst, src);
return MIGRATEPAGE_SUCCESS;
}
diff --git a/include/linux/migrate_mode.h b/include/linux/migrate_mode.h
index f37cc03f9369..9fb482bb7323 100644
--- a/include/linux/migrate_mode.h
+++ b/include/linux/migrate_mode.h
@@ -7,16 +7,11 @@
* on most operations but not ->writepage as the potential stall time
* is too significant
* MIGRATE_SYNC will block when migrating pages
- * MIGRATE_SYNC_NO_COPY will block when migrating pages but will not copy pages
- * with the CPU. Instead, page copy happens outside the migratepage()
- * callback and is likely using a DMA engine. See migrate_vma() and HMM
- * (mm/hmm.c) for users of this mode.
*/
enum migrate_mode {
MIGRATE_ASYNC,
MIGRATE_SYNC_LIGHT,
MIGRATE_SYNC,
- MIGRATE_SYNC_NO_COPY,
};
enum migrate_reason {
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 22c96fed70b5..6597ebea8ae2 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -234,14 +234,6 @@ static int balloon_page_migrate(struct page *newpage, struct page *page,
{
struct balloon_dev_info *balloon = balloon_page_device(page);
- /*
- * We can not easily support the no copy case here so ignore it as it
- * is unlikely to be used with balloon pages. See include/linux/hmm.h
- * for a user of the MIGRATE_SYNC_NO_COPY mode.
- */
- if (mode == MIGRATE_SYNC_NO_COPY)
- return -EINVAL;
-
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
diff --git a/mm/migrate.c b/mm/migrate.c
index ce4142ac8565..6a9bb4af2595 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -697,10 +697,7 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
if (src_private)
folio_attach_private(dst, folio_detach_private(src));
- if (mode != MIGRATE_SYNC_NO_COPY)
- folio_migrate_copy(dst, src);
- else
- folio_migrate_flags(dst, src);
+ folio_migrate_copy(dst, src);
return MIGRATEPAGE_SUCCESS;
}
@@ -929,7 +926,6 @@ static int fallback_migrate_folio(struct address_space *mapping,
/* Only writeback folios in full synchronous migration */
switch (mode) {
case MIGRATE_SYNC:
- case MIGRATE_SYNC_NO_COPY:
break;
default:
return -EBUSY;
@@ -1187,7 +1183,6 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
*/
switch (mode) {
case MIGRATE_SYNC:
- case MIGRATE_SYNC_NO_COPY:
break;
default:
rc = -EBUSY;
@@ -1398,7 +1393,6 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
goto out;
switch (mode) {
case MIGRATE_SYNC:
- case MIGRATE_SYNC_NO_COPY:
break;
default:
goto out;
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b42d3545ca85..6e7967853477 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1752,14 +1752,6 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
unsigned long old_obj, new_obj;
unsigned int obj_idx;
- /*
- * We cannot support the _NO_COPY case here, because copy needs to
- * happen under the zs lock, which does not work with
- * MIGRATE_SYNC_NO_COPY workflow.
- */
- if (mode == MIGRATE_SYNC_NO_COPY)
- return -EINVAL;
-
VM_BUG_ON_PAGE(!PageIsolated(page), page);
/* The page is locked, so this pointer must remain valid */
--
2.27.0
