+ hugetlb-only-set-hpagemigratable-for-migratable-hstates.patch added to -mm tree

+ hugetlb-only-set-hpagemigratable-for-migratable-hstates.patch added to -mm tree

[akpm]

The patch titled
     Subject: hugetlb: only set HPageMigratable for migratable hstates
has been added to the -mm tree.  Its filename is
     hugetlb-only-set-hpagemigratable-for-migratable-hstates.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/hugetlb-only-set-hpagemigratable-for-migratable-hstates.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/hugetlb-only-set-hpagemigratable-for-migratable-hstates.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Mike Kravetz <mike.kravetz@oracle.com>
Subject: hugetlb: only set HPageMigratable for migratable hstates

The HP_Migratable flag indicates a page is a candidate for migration. 
Only set the flag if the page's hstate supports migration.  This allows
the migration paths to detect non-migratable pages earlier.  If migration
is not supported for the hstate, HP_Migratable will not be set, the page
will not be isolated and no attempt will be made to migrate.  We should
never get to unmap_and_move_huge_page for a page where migration is not
supported, so throw a warning if we do.

Link: https://lkml.kernel.org/r/20210122195231.324857-4-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/hugetlbfs/inode.c    |    2 +-
 include/linux/hugetlb.h |    9 +++++++++
 mm/hugetlb.c            |    8 ++++----
 mm/migrate.c            |    9 ++++-----
 4 files changed, 18 insertions(+), 10 deletions(-)

--- a/fs/hugetlbfs/inode.c~hugetlb-only-set-hpagemigratable-for-migratable-hstates
+++ a/fs/hugetlbfs/inode.c
@@ -735,7 +735,7 @@ static long hugetlbfs_fallocate(struct f
 
 		mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 
-		SetHPageMigratable(page);
+		SetHPageMigratableIfSupported(page);
 		/*
 		 * unlock_page because locked by add_to_page_cache()
 		 * put_page() due to reference from alloc_huge_page()
--- a/include/linux/hugetlb.h~hugetlb-only-set-hpagemigratable-for-migratable-hstates
+++ a/include/linux/hugetlb.h
@@ -741,6 +741,15 @@ static inline bool hugepage_migration_su
 }
 
 /*
+ * Only set HPageMigratable if migration supported for page
+ */
+static inline void SetHPageMigratableIfSupported(struct page *page)
+{
+	if (hugepage_migration_supported(page_hstate(page)))
+		SetHPageMigratable(page);
+}
+
+/*
  * Movability check is different as compared to migration check.
  * It determines whether or not a huge page should be placed on
  * movable zone or not. Movability of any huge page should be
--- a/mm/hugetlb.c~hugetlb-only-set-hpagemigratable-for-migratable-hstates
+++ a/mm/hugetlb.c
@@ -4199,7 +4199,7 @@ retry_avoidcopy:
 				make_huge_pte(vma, new_page, 1));
 		page_remove_rmap(old_page, true);
 		hugepage_add_new_anon_rmap(new_page, vma, haddr);
-		SetHPageMigratable(new_page);
+		SetHPageMigratableIfSupported(new_page);
 		/* Make the old page be freed below */
 		new_page = old_page;
 	}
@@ -4441,7 +4441,7 @@ retry:
 	 * been isolated for migration.
 	 */
 	if (new_page)
-		SetHPageMigratable(page);
+		SetHPageMigratableIfSupported(page);
 
 	unlock_page(page);
 out:
@@ -4752,7 +4752,7 @@ int hugetlb_mcopy_atomic_pte(struct mm_s
 	update_mmu_cache(dst_vma, dst_addr, dst_pte);
 
 	spin_unlock(ptl);
-	SetHPageMigratable(page);
+	SetHPageMigratableIfSupported(page);
 	if (vm_shared)
 		unlock_page(page);
 	ret = 0;
@@ -5596,7 +5596,7 @@ void putback_active_hugepage(struct page
 {
 	VM_BUG_ON_PAGE(!PageHead(page), page);
 	spin_lock(&hugetlb_lock);
-	SetHPageMigratable(page);
+	SetHPageMigratableIfSupported(page);
 	list_move_tail(&page->lru, &(page_hstate(page))->hugepage_activelist);
 	spin_unlock(&hugetlb_lock);
 	put_page(page);
--- a/mm/migrate.c~hugetlb-only-set-hpagemigratable-for-migratable-hstates
+++ a/mm/migrate.c
@@ -1275,13 +1275,12 @@ static int unmap_and_move_huge_page(new_
 	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.
+	 * Support for migration should be checked at isolation time.
+	 * Therefore, we should never get here if migration is not supported
+	 * for the page.
 	 */
 	if (!hugepage_migration_supported(page_hstate(hpage))) {
+		VM_WARN_ON(1);
 		list_move_tail(&hpage->lru, ret);
 		return -ENOSYS;
 	}
_

Patches currently in -mm which might be from mike.kravetz@oracle.com are

hugetlb-use-pageprivate-for-hugetlb-specific-page-flags.patch
hugetlb-convert-page_huge_active-hpagemigratable-flag.patch
hugetlb-only-set-hpagemigratable-for-migratable-hstates.patch
hugetlb-convert-pagehugetemporary-to-hpagetemporary-flag.patch
hugetlb-convert-pagehugefreed-to-hpagefreed-flag.patch
mm-hugetlb-change-hugetlb_reserve_pages-to-type-bool.patch
hugetlbfs-remove-special-hugetlbfs_set_page_dirty.patch