mm/smaps: fix race between smaps_hugetlb_range and migration

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: mm/smaps: fix race between smaps_hugetlb_range and migration smaps_hugetlb_range() handles the pte without holdling ptl, and may be concurrenct with migration, leaing to BUG_ON in pfn_swap_entry_to_page(). The race is as follows. smaps_hugetlb_range migrate_pages huge_ptep_get remove_migration_ptes folio_unlock pfn_swap_entry_folio BUG_ON To fix it, hold ptl lock in smaps_hugetlb_range().

References

• https://git.kernel.org/stable/c/2a1f3663974162b8f1e098196f557cfc1d160138
• https://git.kernel.org/stable/c/09fc018f48871123ad5dbd7b03c956580232ed76
• https://git.kernel.org/stable/c/b625883ccbcc2b57808db51d1375b1d7b9bcb3e5
• https://git.kernel.org/stable/c/45d19b4b6c2d422771c29b83462d84afcbb33f01