From nobody Wed Sep 10 06:52:05 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 14D62C0015E for ; Tue, 1 Aug 2023 22:08:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232771AbjHAWIP (ORCPT ); Tue, 1 Aug 2023 18:08:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231478AbjHAWIJ (ORCPT ); Tue, 1 Aug 2023 18:08:09 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 098F1268F for ; Tue, 1 Aug 2023 15:07:51 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-57320c10635so71725447b3.3 for ; Tue, 01 Aug 2023 15:07:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1690927671; x=1691532471; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=FgBjF0ZO5ynPdNrndPmrtDmv0LneRZKTmqqgx6E5wg8=; b=D1O6U13IyQtW6sRKIgsBESsntgiHZD2NBKEqY9x4VzN/LKKhnlNfxDelhOtdMckxRn FHM+qzWy+1vIGVvjuSnC3HOPacbJwiF+FU/44s3FUSl9rg9/MlksilEUDdYILducKN5m QBspm1K1gtu0F9WcdyEIrEuwnPMiQ8okMkqevL/Euzqha1FW9VFmXK9Kd09SaJL8SIMi 4XcGgId5NKrdkKLAeWoz/iYiTpXzRmouek8VJ8B5ZERcnA/Lkgi6E3b5jwXkBi9h6gTm 7wI1MoX2O3/0bFhkSpJ1WB6U2kt7rsAJK91S/XGtkVxCLlTHZukUWI5CAAc5iREvhiOQ j9Gg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690927671; x=1691532471; 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=FgBjF0ZO5ynPdNrndPmrtDmv0LneRZKTmqqgx6E5wg8=; b=cArRiACyB0A3L0L1ol/Btjapdf4CDB3q3hT7vH7U8IEwosQuxFvVil1r989yRcZFey H+gw6MDe9AGqynrRtXxivkA5AOqSTouYOHSM8i8yzrujkIItjRfAAoaGM55kRS0YeIFa ybKVLRfaYDhrQOr6Il7ACAfkwLn79ipVrslMFqOL4hETzx1v6AGUiwVJvJ1c1VTgbv0R hRHrYely1e57d5aSFwWKsqayL0Weldc35+4KGtBaLlOPdVK3ck6n/vSg7o/lCXNwmyU2 2bkdsyf1wAzrsxxquKjPHuj5FF1KPkAlEK+uZA2WQ12LjFghfoDc28fH5Q726jK1NqRa M9eQ== X-Gm-Message-State: ABy/qLYXhTz+ydCVMzcJyZWqLFw/A1XyCs1uyt0P7quWzmZ8pOsLGyQP Ux69pAur2+31HNEeoysz0Oli1btywdA= X-Google-Smtp-Source: APBJJlHKCcBKjQ9mL8CtWFWy75AVvvzqEFOjz4RA/pg75yQkmZcpThORh+6C2/yUUDZy/D/HgF30pmifT2Y= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:211c:a2ff:f17b:c5e9]) (user=surenb job=sendgmr) by 2002:a81:ae13:0:b0:583:a866:3450 with SMTP id m19-20020a81ae13000000b00583a8663450mr126859ywh.7.1690927671038; Tue, 01 Aug 2023 15:07:51 -0700 (PDT) Date: Tue, 1 Aug 2023 15:07:32 -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: <20230801220733.1987762-7-surenb@google.com> Subject: [PATCH v2 6/6] mm: move vma locking out of vma_prepare 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 , Linus Torvalds , "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" vma_prepare() is currently the central place where vmas are being locked before vma_complete() applies changes to them. While this is convenient, it also obscures vma locking and makes it hard to follow the locking rules. Move vma locking out of vma_prepare() and take vma locks explicitly at the locations where vmas are being modified. Suggested-by: Linus Torvalds Signed-off-by: Suren Baghdasaryan Reviewed-by: Liam R. Howlett --- mm/mmap.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 850a39dee075..e59d83cb1d7a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -476,16 +476,6 @@ static inline void init_vma_prep(struct vma_prepare *v= p, */ static inline void vma_prepare(struct vma_prepare *vp) { - vma_start_write(vp->vma); - if (vp->adj_next) - vma_start_write(vp->adj_next); - if (vp->insert) - vma_start_write(vp->insert); - if (vp->remove) - vma_start_write(vp->remove); - if (vp->remove2) - vma_start_write(vp->remove2); - if (vp->file) { uprobe_munmap(vp->vma, vp->vma->vm_start, vp->vma->vm_end); =20 @@ -650,6 +640,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area= _struct *vma, bool remove_next =3D false; struct vma_prepare vp; =20 + vma_start_write(vma); if (next && (vma !=3D next) && (end =3D=3D next->vm_end)) { int ret; =20 @@ -657,6 +648,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area= _struct *vma, ret =3D dup_anon_vma(vma, next); if (ret) return ret; + vma_start_write(next); } =20 init_multi_vma_prep(&vp, vma, NULL, remove_next ? next : NULL, NULL); @@ -708,6 +700,8 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area= _struct *vma, if (vma_iter_prealloc(vmi)) return -ENOMEM; =20 + vma_start_write(vma); + init_vma_prep(&vp, vma); vma_prepare(&vp); vma_adjust_trans_huge(vma, start, end, 0); @@ -946,10 +940,12 @@ struct vm_area_struct *vma_merge(struct vma_iterator = *vmi, struct mm_struct *mm, /* Can we merge both the predecessor and the successor? */ if (merge_prev && merge_next && is_mergeable_anon_vma(prev->anon_vma, next->anon_vma, NULL)) { + vma_start_write(next); remove =3D next; /* case 1 */ vma_end =3D next->vm_end; err =3D dup_anon_vma(prev, next); if (curr) { /* case 6 */ + vma_start_write(curr); remove =3D curr; remove2 =3D next; if (!next->anon_vma) @@ -958,6 +954,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *v= mi, struct mm_struct *mm, } else if (merge_prev) { /* case 2 */ if (curr) { err =3D dup_anon_vma(prev, curr); + vma_start_write(curr); if (end =3D=3D curr->vm_end) { /* case 7 */ remove =3D curr; } else { /* case 5 */ @@ -969,6 +966,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *v= mi, struct mm_struct *mm, res =3D next; if (prev && addr < prev->vm_end) { /* case 4 */ vma_end =3D addr; + vma_start_write(next); adjust =3D next; adj_start =3D -(prev->vm_end - addr); err =3D dup_anon_vma(next, prev); @@ -983,6 +981,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *v= mi, struct mm_struct *mm, vma_pgoff =3D next->vm_pgoff - pglen; if (curr) { /* case 8 */ vma_pgoff =3D curr->vm_pgoff; + vma_start_write(curr); remove =3D curr; err =3D dup_anon_vma(next, curr); } @@ -996,6 +995,8 @@ struct vm_area_struct *vma_merge(struct vma_iterator *v= mi, struct mm_struct *mm, if (vma_iter_prealloc(vmi)) return NULL; =20 + vma_start_write(vma); + init_multi_vma_prep(&vp, vma, adjust, remove, remove2); VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && vp.anon_vma !=3D adjust->anon_vma); @@ -2373,6 +2374,9 @@ int __split_vma(struct vma_iterator *vmi, struct vm_a= rea_struct *vma, if (new->vm_ops && new->vm_ops->open) new->vm_ops->open(new); =20 + vma_start_write(vma); + vma_start_write(new); + init_vma_prep(&vp, vma); vp.insert =3D new; vma_prepare(&vp); @@ -3078,6 +3082,8 @@ static int do_brk_flags(struct vma_iterator *vmi, str= uct vm_area_struct *vma, if (vma_iter_prealloc(vmi)) goto unacct_fail; =20 + vma_start_write(vma); + init_vma_prep(&vp, vma); vma_prepare(&vp); vma_adjust_trans_huge(vma, vma->vm_start, addr + len, 0); --=20 2.41.0.585.gd2178a4bd4-goog