From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88633C433EF for ; Mon, 4 Jul 2022 01:33:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232778AbiGDBdl (ORCPT ); Sun, 3 Jul 2022 21:33:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232685AbiGDBdf (ORCPT ); Sun, 3 Jul 2022 21:33:35 -0400 Received: from out0.migadu.com (out0.migadu.com [IPv6:2001:41d0:2:267::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 47AF5FF9 for ; Sun, 3 Jul 2022 18:33:34 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1656898412; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZNgH5eHPcnq/+3rKXXS1c6RWQGb3F3eUFrPlWLShXcQ=; b=SpdN77/fOWWRpW2V7H7g0MG8DDqDeCF63c2jnfpMye/4Uc3Hjg9f13RAOZQYPDt0PsZpE5 t0ZUWIC9KbfO+TAHF0ACpR8RgeJdBfDJKlR5zTnbjWNvbhE/npSw//SM2TXvlpr5YvZxGW Kep2gOytBblyp3HQ7Nv6aGA3vQoyPk4= From: Naoya Horiguchi To: linux-mm@kvack.org Cc: Andrew Morton , David Hildenbrand , Mike Kravetz , Miaohe Lin , Liu Shixin , Yang Shi , Oscar Salvador , Muchun Song , Naoya Horiguchi , linux-kernel@vger.kernel.org Subject: [mm-unstable PATCH v4 2/9] mm/hugetlb: separate path for hwpoison entry in copy_hugetlb_page_range() Date: Mon, 4 Jul 2022 10:33:05 +0900 Message-Id: <20220704013312.2415700-3-naoya.horiguchi@linux.dev> In-Reply-To: <20220704013312.2415700-1-naoya.horiguchi@linux.dev> References: <20220704013312.2415700-1-naoya.horiguchi@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Naoya Horiguchi Originally copy_hugetlb_page_range() handles migration entries and hwpoisoned entries in similar manner. But recently the related code path has more code for migration entries, and when is_writable_migration_entry() was converted to !is_readable_migration_entry(), hwpoison entries on source processes got to be unexpectedly updated (which is legitimate for migration entries, but not for hwpoison entries). This results in unexpected serious issues like kernel panic when forking processes with hwpoison entries in pmd. Separate the if branch into one for hwpoison entries and one for migration entries. Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") Signed-off-by: Naoya Horiguchi Reviewed-by: Miaohe Lin Reviewed-by: Mike Kravetz Reviewed-by: Muchun Song Cc: # 5.18 --- v3 -> v4: - replact set_huge_swap_pte_at() with set_huge_pte_at() --- mm/hugetlb.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index bdc4499f324b..ad621688370b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4803,8 +4803,13 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src, * sharing with another vma. */ ; - } else if (unlikely(is_hugetlb_entry_migration(entry) || - is_hugetlb_entry_hwpoisoned(entry))) { + } else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) { + bool uffd_wp = huge_pte_uffd_wp(entry); + + if (!userfaultfd_wp(dst_vma) && uffd_wp) + entry = huge_pte_clear_uffd_wp(entry); + set_huge_pte_at(dst, addr, dst_pte, entry); + } else if (unlikely(is_hugetlb_entry_migration(entry))) { swp_entry_t swp_entry = pte_to_swp_entry(entry); bool uffd_wp = huge_pte_uffd_wp(entry); -- 2.25.1