Re: [PATCH] mm: remove migration for HugePage in isolate_single_pageblock()

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 16 Aug 2024 12:06:25 +0800 Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> The gigantic page size may larger than memory block size, so memory
> offline always fails in this case after commit b2c9e2fbba32 ("mm: make
> alloc_contig_range work at pageblock granularity"),
> 
> offline_pages
>   start_isolate_page_range
>     start_isolate_page_range(isolate_before=true)
>       isolate [isolate_start, isolate_start + pageblock_nr_pages)
>     start_isolate_page_range(isolate_before=false)
>       isolate [isolate_end - pageblock_nr_pages, isolate_end) pageblock
>        	__alloc_contig_migrate_range
>           isolate_migratepages_range
>             isolate_migratepages_block
>               isolate_or_dissolve_huge_page
>                 if (hstate_is_gigantic(h))
>                     return -ENOMEM;
> 
> In fact, we don't need to migrate page in page range isolation, for
> memory offline path, there is do_migrate_range() to move the pages.
> For contig allocation, there is another __alloc_contig_migrate_range()
> after isolation to migrate the pages. So fix issue by skipping the
> __alloc_contig_migrate_range() in isolate_single_pageblock().
> 
> Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock granularity")

Should we backport this into -stable kernels?