From: Zi Yan <zi.yan@xxxxxxxxxxxxxx> Subject: mm/huge_memory.c: deposit page table when copying a PMD migration entry We need to deposit pre-allocated PTE page table when a PMD migration entry is copied in copy_huge_pmd(). Otherwise, we will leak the pre-allocated page and cause a NULL pointer dereference later in zap_huge_pmd(). The missing counters during PMD migration entry copy process are added as well. The bug report is here: https://lkml.org/lkml/2017/10/29/214 Link: http://lkml.kernel.org/r/20171030144636.4836-1-zi.yan@xxxxxxxx Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path") Signed-off-by: Zi Yan <zi.yan@xxxxxxxxxxxxxx> Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/huge_memory.c | 3 +++ 1 file changed, 3 insertions(+) diff -puN mm/huge_memory.c~mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry mm/huge_memory.c --- a/mm/huge_memory.c~mm-migration-deposit-page-table-when-copying-a-pmd-migration-entry +++ a/mm/huge_memory.c @@ -941,6 +941,9 @@ int copy_huge_pmd(struct mm_struct *dst_ pmd = pmd_swp_mksoft_dirty(pmd); set_pmd_at(src_mm, addr, src_pmd, pmd); } + add_mm_counter(dst_mm, MM_ANONPAGES, HPAGE_PMD_NR); + atomic_long_inc(&dst_mm->nr_ptes); + pgtable_trans_huge_deposit(dst_mm, dst_pmd, pgtable); set_pmd_at(dst_mm, addr, dst_pmd, pmd); ret = 0; goto out_unlock; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
