From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id B78D96B0038 for ; Mon, 30 Oct 2017 10:46:39 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id z3so6192301wme.21 for ; Mon, 30 Oct 2017 07:46:39 -0700 (PDT) Received: from out4-smtp.messagingengine.com (out4-smtp.messagingengine.com. [66.111.4.28]) by mx.google.com with ESMTPS id b45si12195007wrg.225.2017.10.30.07.46.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Oct 2017 07:46:38 -0700 (PDT) From: Zi Yan Subject: [PATCH] mm: migration: deposit page table when copying a PMD migration entry. Date: Mon, 30 Oct 2017 10:46:36 -0400 Message-Id: <20171030144636.4836-1-zi.yan@sent.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: "Kirill A . Shutemov" , Zi Yan , Fengguang Wu From: Zi Yan 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 Fixes: 84c3fc4e9c563 ("mm: thp: check pmd migration entry in common path") Reported-by: Fengguang Wu Signed-off-by: Zi Yan Cc: Kirill A. Shutemov --- mm/huge_memory.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 269b5df58543..1981ed697dab 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -941,6 +941,9 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, 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; -- 2.14.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org