From nobody Wed Sep 10 09:29:26 2025 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 E1E59C0015E for ; Tue, 1 Aug 2023 22:08:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232224AbjHAWIA (ORCPT ); Tue, 1 Aug 2023 18:08:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231926AbjHAWHu (ORCPT ); Tue, 1 Aug 2023 18:07:50 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AFF61BC3 for ; Tue, 1 Aug 2023 15:07:49 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-5840614b107so75693947b3.1 for ; Tue, 01 Aug 2023 15:07:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1690927668; x=1691532468; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=QxBrE/UCHWlQTdGOylRc3uDNTY7RNXyaur9L23gJy4g=; b=LGbOmtH0lMhdDYO3+2ECExEYuxVvpb5dUlLecAiJAGrPI9PAJfTN7UrlhG2D2+sMgI A0HPsE7Dh7snipQv/ppKfZkrtywqFIDj94GgYYg1RmHEKQD/JrUFvPL4mXaNgmgR43fS rzNN/7cPcSEEUD6MphOEKlUIyUYRI9RNEW1ibPgtDMhMmPz+MaEiw+C/wPcvGj3gdm+s wmBOfyKZ9Eq/c9nMUYmgRF+ijS83GqRJwTrxNUo/kn28ipzSQ7VAbYmtkG9fCdYkXi0z Hhzh6iMenp89gYpIovNtlhgbKlD0/7Qoap5BixiG9npmNeurITeJhKlGDSUEA6RAa5bC 2mng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690927668; x=1691532468; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=QxBrE/UCHWlQTdGOylRc3uDNTY7RNXyaur9L23gJy4g=; b=Ap1x9hm3PT8GMK937q1zhkKCDQy2c843axWqM+u6Ui0pCmvUssMZWA0JFT8JbdISkD 8XN8GHcOMzKCClzm1MUAuT6F3ELlg+8Ub/62ciezlFqjdLDR4KDdBVf1Wh9tMZfyFWdB I1JSLiY9lMuNE0SD1mI7PmnX/0am/HAT4MGdMXBe4E6PblSNbUyhMciNclFik4xWzip/ d5XUkyDXQ8JzRUWzUr2NflFth9obtnI/+T0yf/wNnp8rz0FAcAyPBj16mj256X7EXw2X 0acOJAfH6GVo05s2do9Beb0tzEgqhGR17U7BF09B1rycGScC5nqmjgN0LL4EacMOc+FS Nl+g== X-Gm-Message-State: ABy/qLbendCnW0g3QhKc4siJGqrfh2S1YxE4xFWLChquogd/9wgzVXSg LnBknTbQ1YHUbRVFTyaVv0+gYNsXUmo= X-Google-Smtp-Source: APBJJlFGce4m/S34cz0bw8Xemucsi7OipxmEL+9L+engD7fhL2P1Th2X8JjKAj9JtV2822hEHcXYgtjOeKk= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:211c:a2ff:f17b:c5e9]) (user=surenb job=sendgmr) by 2002:a81:ae02:0:b0:576:b244:5a4e with SMTP id m2-20020a81ae02000000b00576b2445a4emr129366ywh.10.1690927668528; Tue, 01 Aug 2023 15:07:48 -0700 (PDT) Date: Tue, 1 Aug 2023 15:07:31 -0700 In-Reply-To: <20230801220733.1987762-1-surenb@google.com> Mime-Version: 1.0 References: <20230801220733.1987762-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.585.gd2178a4bd4-goog Message-ID: <20230801220733.1987762-6-surenb@google.com> Subject: [PATCH v2 5/6] mm: always lock new vma before inserting into vma tree From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org, jannh@google.com, willy@infradead.org, liam.howlett@oracle.com, david@redhat.com, peterx@redhat.com, ldufour@linux.ibm.com, vbabka@suse.cz, michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, hannes@cmpxchg.org, dave@stgolabs.net, hughd@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, Suren Baghdasaryan Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" While it's not strictly necessary to lock a newly created vma before adding it into the vma tree (as long as no further changes are performed to it), it seems like a good policy to lock it and prevent accidental changes after it becomes visible to the page faults. Lock the vma before adding it into the vma tree. Suggested-by: Jann Horn Signed-off-by: Suren Baghdasaryan Reviewed-by: Liam R. Howlett --- mm/mmap.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 3937479d0e07..850a39dee075 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -412,6 +412,8 @@ static int vma_link(struct mm_struct *mm, struct vm_are= a_struct *vma) if (vma_iter_prealloc(&vmi)) return -ENOMEM; =20 + vma_start_write(vma); + if (vma->vm_file) { mapping =3D vma->vm_file->f_mapping; i_mmap_lock_write(mapping); @@ -477,7 +479,8 @@ static inline void vma_prepare(struct vma_prepare *vp) vma_start_write(vp->vma); if (vp->adj_next) vma_start_write(vp->adj_next); - /* vp->insert is always a newly created VMA, no need for locking */ + if (vp->insert) + vma_start_write(vp->insert); if (vp->remove) vma_start_write(vp->remove); if (vp->remove2) @@ -3098,6 +3101,7 @@ static int do_brk_flags(struct vma_iterator *vmi, str= uct vm_area_struct *vma, vma->vm_pgoff =3D addr >> PAGE_SHIFT; vm_flags_init(vma, flags); vma->vm_page_prot =3D vm_get_page_prot(flags); + vma_start_write(vma); if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL)) goto mas_store_fail; =20 @@ -3345,7 +3349,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct= **vmap, get_file(new_vma->vm_file); if (new_vma->vm_ops && new_vma->vm_ops->open) new_vma->vm_ops->open(new_vma); - vma_start_write(new_vma); if (vma_link(mm, new_vma)) goto out_vma_link; *need_rmap_locks =3D false; --=20 2.41.0.585.gd2178a4bd4-goog