From nobody Thu Sep 11 15:26:07 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 668A8EB64DD for ; Thu, 3 Aug 2023 17:27:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234925AbjHCR1X (ORCPT ); Thu, 3 Aug 2023 13:27:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234818AbjHCR1L (ORCPT ); Thu, 3 Aug 2023 13:27:11 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC2963C16 for ; Thu, 3 Aug 2023 10:27:07 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-d074da73c3eso1372781276.3 for ; Thu, 03 Aug 2023 10:27:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1691083627; x=1691688427; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=GZEu7FQxJMwmMQ2ZbaGaDze4HsujzOay4eQMS+qpos8=; b=iMlvdhm/bxVV7kv0V79kx1hxAyb+1GfcPnJNgAo6LGdR0bN5ykKWLzgwRkr0IsKULR 2o34cI0Yf3y9b3S2Dr1CwRyv6f01fPNaOoXOCMRAQbhpK1DPGFgCjTrhlWjoMsqAvyL0 8VUIztQRc1OQyCbz5DagmCU/mu3dLq6uVQlfq3eZNISYdHHkvNHZJzuMW6YuKo90+kyC hjZ+CUef9CzPm33relwkpyOY3ShX8wwK6g3JLpiI+W0wl5DrWoPM2vnAEuwmowfvDdjR SwLvk9fJF/d9WaXsmtAEQnK/vJCJQgoZOjJbm+glRWLSwwbs7FTj9oR+NIkDHwsI3k9/ MBMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691083627; x=1691688427; 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=GZEu7FQxJMwmMQ2ZbaGaDze4HsujzOay4eQMS+qpos8=; b=gym2yatDLXopktTQ3D5GGwbjbq79JRjNjcfMRG7gmtWdu33WQ8Yy4hRzdd2nJfBpf5 QNCeZdrCERPUsQdaxwC/smGWUOK4gxz+mj0fBHCQ1J3v/v7gVTS8cKYtTQ5+cAOJNDFd uSJ4oOhNM0ir/3mh9dkvFpFLkqNR+NB7vI4Y0F66871fba5Z2eud9Z4aqBh6z14/RChm wLxdXuVFHMcPZoMECuTwbylzqqzEUe2HWvCtgmpCgY1y0HCs5YGDOIa1qmUbOThowWNJ VYhxwotmtxVuci8FBwibJOAKK8wBzL8vsa22o5W1vi1e26uztwkeOwckvkm5wjMpRr4Q CA5A== X-Gm-Message-State: ABy/qLZYA61oBxdtXDzxL71dF4StPrjQ8jDiwTV8OtFpxZfoWLdXLXxt eSDh2W2cWvZXAebZePqETXruNLqmKYc= X-Google-Smtp-Source: APBJJlEm+TAFgwKeycGXNkE9sZYz1YS9giHD/D1paY/qC/rrcXYAkNTs0f2pZWBHAJYKXSdQl1MdNfKRQzw= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:3dec:ef9e:7bf4:7a6]) (user=surenb job=sendgmr) by 2002:a25:19c2:0:b0:d0d:1563:58f2 with SMTP id 185-20020a2519c2000000b00d0d156358f2mr129793ybz.2.1691083627024; Thu, 03 Aug 2023 10:27:07 -0700 (PDT) Date: Thu, 3 Aug 2023 10:26:50 -0700 In-Reply-To: <20230803172652.2849981-1-surenb@google.com> Mime-Version: 1.0 References: <20230803172652.2849981-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.585.gd2178a4bd4-goog Message-ID: <20230803172652.2849981-6-surenb@google.com> Subject: [PATCH v3 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 , "Liam R . Howlett" 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