mm: hugetlb_vmemmap: fix a race between vmemmap pmd split

The local variable @page in __split_vmemmap_huge_pmd() to obtain a pmd
page without holding page_table_lock may possiblely get the page table
page instead of a huge pmd page.

The effect may be in set_pte_at() since we may pass an invalid page
struct, if set_pte_at() wants to access the page struct (e.g. 
CONFIG_PAGE_TABLE_CHECK is enabled), it may crash the kernel.

So fix it.  And inline __split_vmemmap_huge_pmd() since it only has one
user.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: d8d55f5616cf ("mm: sparsemem: use page table lock to protect kernel pmd operations")
Signed-off-by: Muchun Song <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions