From: Miaohe Lin <linmiaohe@xxxxxxxxxx> Subject: mm/rmap: fix potential pte_unmap on an not mapped pte For PMD-mapped page (usually THP), pvmw->pte is NULL. For PTE-mapped THP, pvmw->pte is mapped. But for HugeTLB pages, pvmw->pte is not mapped and set to the relevant page table entry. So in page_vma_mapped_walk_done(), we may do pte_unmap() for HugeTLB pte which is not mapped. Fix this by checking pvmw->page against PageHuge before trying to do pte_unmap(). Link: https://lkml.kernel.org/r/20210127093349.39081-1-linmiaohe@xxxxxxxxxx Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()") Signed-off-by: Hongxiang Lou <louhongxiang@xxxxxxxxxx> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx> Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Nathan Chancellor <natechancellor@xxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Michel Lespinasse <walken@xxxxxxxxxx> Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx> Cc: Brian Geffon <bgeffon@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/rmap.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/include/linux/rmap.h~mm-rmap-fix-potential-pte_unmap-on-an-not-mapped-pte +++ a/include/linux/rmap.h @@ -213,7 +213,8 @@ struct page_vma_mapped_walk { static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw) { - if (pvmw->pte) + /* HugeTLB pte is set to the relevant page table entry without pte_mapped. */ + if (pvmw->pte && !PageHuge(pvmw->page)) pte_unmap(pvmw->pte); if (pvmw->ptl) spin_unlock(pvmw->ptl); _
