mm: migration: fix the FOLL_GET failure on following huge page

Not all huge page APIs support FOLL_GET option, so move_pages() syscall
will fail to get the page node information for some huge pages.

Like x86 on linux 5.19 with 1GB huge page API follow_huge_pud(), it will
return NULL page for FOLL_GET when calling move_pages() syscall with the
NULL 'nodes' parameter, the 'status' parameter has '-2' error in array.

Note: follow_huge_pud() now supports FOLL_GET in linux 6.0.
      Link: https://lore.kernel.org/all/[email protected]

But these huge page APIs don't support FOLL_GET:
  1. follow_huge_pud() in arch/s390/mm/hugetlbpage.c
  2. follow_huge_addr() in arch/ia64/mm/hugetlbpage.c
     It will cause WARN_ON_ONCE for FOLL_GET.
  3. follow_huge_pgd() in mm/hugetlb.c

This is an temporary solution to mitigate the side effect of the race
condition fix by calling follow_page() with FOLL_GET set for huge pages.

After supporting follow huge page by FOLL_GET is done, this fix can be
reverted safely.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racing with memory offline")
Signed-off-by: Haiyue Wang <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Reviewed-by: "Huang, Ying" <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Muchun Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions