+ mm-migrate-remove-pagetranshuge-check-in-numamigrate_isolate_page.patch added to mm-unstable branch

+ mm-migrate-remove-pagetranshuge-check-in-numamigrate_isolate_page.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: migrate: remove PageTransHuge check in numamigrate_isolate_page()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-migrate-remove-pagetranshuge-check-in-numamigrate_isolate_page.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-migrate-remove-pagetranshuge-check-in-numamigrate_isolate_page.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: Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: mm: migrate: remove PageTransHuge check in numamigrate_isolate_page()
Date: Wed, 13 Sep 2023 17:51:24 +0800

Patch series "mm: migrate: more folio conversion and unification", v3.

Convert more migrate functions to use a folio, it is also a preparation
for large folio migration support when balancing numa.


This patch (of 8):

The assert VM_BUG_ON_PAGE(order && !PageTransHuge(page), page) is not very
useful,

   1) for a tail/base page, order = 0, for a head page, the order > 0 &&
      PageTransHuge() is true
   2) there is a PageCompound() check and only base page is handled in
      do_numa_page(), and do_huge_pmd_numa_page() only handle PMD-mapped
      THP
   3) even though the page is a tail page, isolate_lru_page() will post
      a warning, and fail to isolate the page
   4) if large folio/pte-mapped THP migration supported in the future,
      we could migrate the entire folio if numa fault on a tail page

so just remove the check.

Link: https://lkml.kernel.org/r/20230913095131.2426871-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20230913095131.2426871-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |    2 --
 1 file changed, 2 deletions(-)

--- a/mm/migrate.c~mm-migrate-remove-pagetranshuge-check-in-numamigrate_isolate_page
+++ a/mm/migrate.c
@@ -2483,8 +2483,6 @@ static int numamigrate_isolate_page(pg_d
 	int nr_pages = thp_nr_pages(page);
 	int order = compound_order(page);
 
-	VM_BUG_ON_PAGE(order && !PageTransHuge(page), page);
-
 	/* Do not migrate THP mapped by multiple processes */
 	if (PageTransHuge(page) && total_mapcount(page) > 1)
 		return 0;
_

Patches currently in -mm which might be from wangkefeng.wang@huawei.com are

mm-migrate-remove-pagetranshuge-check-in-numamigrate_isolate_page.patch
mm-migrate-remove-thp-mapcount-check-in-numamigrate_isolate_page.patch
mm-migrate-convert-numamigrate_isolate_page-to-numamigrate_isolate_folio.patch
mm-migrate-convert-migrate_misplaced_page-to-migrate_misplaced_folio.patch
mm-migrate-use-__folio_test_movable.patch
mm-migrate-use-a-folio-in-add_page_for_migration.patch
mm-migrate-remove-pagehead-check-for-hugetlb-in-add_page_for_migration.patch
mm-migrate-remove-isolated-variable-in-add_page_for_migration.patch