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mm: remove MIGRATE_SYNC_NO_COPY mode

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Commit 2916ecc0f9 ("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.

Link: https://lkml.kernel.org/r/20240524052843.182275-6-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Jane Chu <jane.chu@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jiaqi Yan <jiaqiyan@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kefeng Wang 2024-05-24 13:28:43 +08:00 committed by Andrew Morton
parent 940d6683c7
commit 906632843d
6 changed files with 3 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
fs/aio.c
View File

@ -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);

5
fs/hugetlbfs/inode.c
View File

@ -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;
}

5
include/linux/migrate_mode.h
View File

@ -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 {

8
mm/balloon_compaction.c
View File

@ -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);

8
mm/migrate.c
View File

@ -671,10 +671,7 @@ 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;
}
@ -903,7 +900,6 @@ 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;
@ -1161,7 +1157,6 @@ 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;
@ -1372,7 +1367,6 @@ 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;

8
mm/zsmalloc.c
View File

@ -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 */