The patch titled
Subject: migrate_pages: move THP/hugetlb migration support check to simplify code
has been added to the -mm mm-unstable branch. Its filename is
migrate_pages-move-thp-hugetlb-migration-support-check-to-simplify-code.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/migrate_pages-move-thp-hugetlb-migration-support-check-to-simplify-code.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: migrate_pages: move THP/hugetlb migration support check to simplify code
Date: Mon, 13 Feb 2023 20:34:44 +0800
This is a code cleanup patch, no functionality change is expected. After
the change, the line number reduces especially in the long
migrate_pages_batch().
Link: https://lkml.kernel.org/r/20230213123444.155149-10-ying.huang@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Suggested-by: Alistair Popple <apopple@xxxxxxxxxx>
Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: Yang Shi <shy828301@xxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Bharata B Rao <bharata@xxxxxxx>
Cc: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/migrate.c~migrate_pages-move-thp-hugetlb-migration-support-check-to-simplify-code
+++ a/mm/migrate.c
@@ -1117,9 +1117,6 @@ static int migrate_folio_unmap(new_page_
bool locked = false;
bool dst_locked = false;
- if (!thp_migration_supported() && folio_test_transhuge(src))
- return -ENOSYS;
-
if (folio_ref_count(src) == 1) {
/* Folio was freed from under us. So we are done. */
folio_clear_active(src);
@@ -1380,16 +1377,6 @@ static int unmap_and_move_huge_page(new_
struct anon_vma *anon_vma = NULL;
struct address_space *mapping = NULL;
- /*
- * Migratability of hugepages depends on architectures and their size.
- * This check is necessary because some callers of hugepage migration
- * like soft offline and memory hotremove don't walk through page
- * tables or check whether the hugepage is pmd-based or not before
- * kicking migration.
- */
- if (!hugepage_migration_supported(page_hstate(hpage)))
- return -ENOSYS;
-
if (folio_ref_count(src) == 1) {
/* page was freed from under us. So we are done. */
folio_putback_active_hugetlb(src);
@@ -1556,6 +1543,20 @@ static int migrate_hugetlbs(struct list_
cond_resched();
+ /*
+ * Migratability of hugepages depends on architectures and
+ * their size. This check is necessary because some callers
+ * of hugepage migration like soft offline and memory
+ * hotremove don't walk through page tables or check whether
+ * the hugepage is pmd-based or not before kicking migration.
+ */
+ if (!hugepage_migration_supported(folio_hstate(folio))) {
+ nr_failed++;
+ stats->nr_failed_pages += nr_pages;
+ list_move_tail(&folio->lru, ret_folios);
+ continue;
+ }
+
rc = unmap_and_move_huge_page(get_new_page,
put_new_page, private,
&folio->page, pass > 2, mode,
@@ -1565,16 +1566,9 @@ static int migrate_hugetlbs(struct list_
* Success: hugetlb folio will be put back
* -EAGAIN: stay on the from list
* -ENOMEM: stay on the from list
- * -ENOSYS: stay on the from list
* Other errno: put on ret_folios list
*/
switch(rc) {
- case -ENOSYS:
- /* Hugetlb migration is unsupported */
- nr_failed++;
- stats->nr_failed_pages += nr_pages;
- list_move_tail(&folio->lru, ret_folios);
- break;
case -ENOMEM:
/*
* When memory is low, don't bother to try to migrate
@@ -1664,6 +1658,28 @@ retry:
cond_resched();
+ /*
+ * Large folio migration might be unsupported or
+ * the allocation might be failed so we should retry
+ * on the same folio with the large folio split
+ * to normal folios.
+ *
+ * Split folios are put in split_folios, and
+ * we will migrate them after the rest of the
+ * list is processed.
+ */
+ if (!thp_migration_supported() && is_thp) {
+ nr_large_failed++;
+ stats->nr_thp_failed++;
+ if (!try_split_folio(folio, &split_folios)) {
+ stats->nr_thp_split++;
+ continue;
+ }
+ stats->nr_failed_pages += nr_pages;
+ list_move_tail(&folio->lru, ret_folios);
+ continue;
+ }
+
rc = migrate_folio_unmap(get_new_page, put_new_page, private,
folio, &dst, pass > 2, avoid_force_lock,
mode, reason, ret_folios);
@@ -1675,36 +1691,9 @@ retry:
* -EAGAIN: stay on the from list
* -EDEADLOCK: stay on the from list
* -ENOMEM: stay on the from list
- * -ENOSYS: stay on the from list
* Other errno: put on ret_folios list
*/
switch(rc) {
- /*
- * Large folio migration might be unsupported or
- * the allocation could've failed so we should retry
- * on the same folio with the large folio split
- * to normal folios.
- *
- * Split folios are put in split_folios, and
- * we will migrate them after the rest of the
- * list is processed.
- */
- case -ENOSYS:
- /* Large folio migration is unsupported */
- if (is_large) {
- nr_large_failed++;
- stats->nr_thp_failed += is_thp;
- if (!try_split_folio(folio, &split_folios)) {
- stats->nr_thp_split += is_thp;
- break;
- }
- } else if (!no_split_folio_counting) {
- nr_failed++;
- }
-
- stats->nr_failed_pages += nr_pages;
- list_move_tail(&folio->lru, ret_folios);
- break;
case -ENOMEM:
/*
* When memory is low, don't bother to try to migrate
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
migrate_pages-organize-stats-with-struct-migrate_pages_stats.patch
migrate_pages-separate-hugetlb-folios-migration.patch
migrate_pages-restrict-number-of-pages-to-migrate-in-batch.patch
migrate_pages-split-unmap_and_move-to-_unmap-and-_move.patch
migrate_pages-batch-_unmap-and-_move.patch
migrate_pages-move-migrate_folio_unmap.patch
migrate_pages-share-more-code-between-_unmap-and-_move.patch
migrate_pages-batch-flushing-tlb.patch
migrate_pages-move-thp-hugetlb-migration-support-check-to-simplify-code.patch
