From nobody Mon Sep 15 23:19:50 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 E42DBC6379F for ; Mon, 9 Jan 2023 20:56:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237767AbjAIU4Y (ORCPT ); Mon, 9 Jan 2023 15:56:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237715AbjAIUze (ORCPT ); Mon, 9 Jan 2023 15:55:34 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 957307458B for ; Mon, 9 Jan 2023 12:54:32 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id y66-20020a25c845000000b00733b5049b6fso10232847ybf.3 for ; Mon, 09 Jan 2023 12:54:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=FDedOk4BDhI0jXVeiXMnt29MYEOAHvgEHolCeEtDVh8=; b=m9qNPQfvAaSk/cZYvrILeQolkFuo8oX0rPOdz+ZeBZe0viaaMWSs2xM9wojEerSzR9 Ehc0liLdN4Rf9t9ITHbgyUo/TpjLKodzNOt3cYyWGhisrg0tQj8O7DOpS0TtK3tPQLQG qUB/3EWr0qIxJ9v9dQ2Qpf6kyj6P77wOGaZ+XxUB3NlRJ4nvQo0f4D36W3MPMO4ktFMc ysLVV5w6Mp+QnxSVtHOQDDwbxZ7kpIUBpnDdTFd6J6q0MuwMTyvve19XzRy6+EFEsY7p 5CEU/qiYVWTESVV3KMWaGXvUZnEBFFh/Tdv+49ubumcalCQjcVJZu4o8Eo8hhtY4lcfd RRGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; 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=FDedOk4BDhI0jXVeiXMnt29MYEOAHvgEHolCeEtDVh8=; b=OUuTXtNvUDVWu6R5zX/GeqhSGq96BSGhtqdFA7FfooxyTv4V/fh4aO4L/eu/lutw6b bMqKwAGut14W14Q0gxn7Hpw3oxWEigGQ2rIVh6lHFwTGNO9Vg74YMMUU+SFSF14HSIJ4 IvcfK1Jykh/37DOicMA/cF4QjAhwWBzXUK/gAZBX7Fgjyj5LvidiF+tNyG4EDT3FrfqT 6tJj2Dyttp7k/R4sO1ZBi0rvaj81jZO60/x2VzhsjU6cJOBb1byw1swSxYYgUMmntjpd ZTswJMZPj+ltefoDVfNz8/oNeiWalrupZk54p7PpA3bYfy/xIf8U6wgebfqOW8KIiVhc t6QA== X-Gm-Message-State: AFqh2krKGAPZSFn31H5N0Y67TD+OEGt/BsZaciihR/3M2rn61hOOGc0w uXTsvpJcQXVo51M9nE8XknvwvuV1EPE= X-Google-Smtp-Source: AMrXdXvGyOxiOv+MuSWvovzrd0so3mEpN1Edvcx+Z2HBXoeLvz+P6Hw4SXaxw2akuo9mk6+zHwkliVPrxQU= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:9393:6f7a:d410:55ca]) (user=surenb job=sendgmr) by 2002:a25:1489:0:b0:6fb:ef1e:bb1a with SMTP id 131-20020a251489000000b006fbef1ebb1amr6925224ybu.168.1673297671808; Mon, 09 Jan 2023 12:54:31 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:15 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230109205336.3665937-21-surenb@google.com> Subject: [PATCH 20/41] mm/mmap: write-lock VMAs in vma_adjust From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com 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_adjust modifies a VMA and possibly its neighbors. Write-lock them before making the modifications. Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index f6ca4a87f9e2..1e2154137631 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -614,6 +614,12 @@ inline int vma_expand(struct ma_state *mas, struct vm_= area_struct *vma, * The following helper function should be used when such adjustments * are necessary. The "insert" vma (if any) is to be inserted * before we drop the necessary locks. + * 'expand' vma is always locked before it's passed to __vma_adjust() + * from vma_merge() because vma should not change from the moment + * can_vma_merge_{before|after} decision is made. + * 'insert' vma is used only by __split_vma() and it's always a brand + * new vma which is not yet added into mm's vma tree, therefore no need + * to lock it. */ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert, @@ -633,6 +639,10 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned = long start, MA_STATE(mas, &mm->mm_mt, 0, 0); struct vm_area_struct *exporter =3D NULL, *importer =3D NULL; =20 + vma_write_lock(vma); + if (next) + vma_write_lock(next); + if (next && !insert) { if (end >=3D next->vm_end) { /* @@ -676,8 +686,11 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned = long start, * If next doesn't have anon_vma, import from vma after * next, if the vma overlaps with it. */ - if (remove_next =3D=3D 2 && !next->anon_vma) + if (remove_next =3D=3D 2 && !next->anon_vma) { exporter =3D next_next; + if (exporter) + vma_write_lock(exporter); + } =20 } else if (end > next->vm_start) { /* @@ -850,6 +863,8 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned l= ong start, if (remove_next =3D=3D 2) { remove_next =3D 1; next =3D next_next; + if (next) + vma_write_lock(next); goto again; } } --=20 2.39.0