On Wed, 13 Mar 2024, Sasha Levin wrote:
> From: Kefeng Wang <wangkefeng.wang@huawei.com>
>
> [ Upstream commit a8ac4a767dcd9d87d8229045904d9fe15ea5e0e8 ]
>
> 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>
> Stable-dep-of: 2774f256e7c0 ("mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index")
No it is not: that one is appropriate to include, this one is not.
Hugh
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> mm/migrate.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index b4d972d80b10c..6f8ad6b64c9bc 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2506,8 +2506,6 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page)
> 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;
> --
> 2.43.0
>
>