From nobody Tue Apr 7 10:39:53 2026 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 41150ECAAD2 for ; Mon, 29 Aug 2022 21:26:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229959AbiH2V0v (ORCPT ); Mon, 29 Aug 2022 17:26:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229881AbiH2V03 (ORCPT ); Mon, 29 Aug 2022 17:26:29 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7BCD8870A0 for ; Mon, 29 Aug 2022 14:25:58 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id e11-20020a17090a630b00b001f8b2deb88dso10114750pjj.1 for ; Mon, 29 Aug 2022 14:25:58 -0700 (PDT) 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; bh=iuFA+HN3YQAhGF4lKe/pszwBtaIFpTgsToRqXaNjG7k=; b=OQFmY5p6Pe2rtWh8HoOtibHP8P5GG7l2q0OSc7HNXnd2wSmQX9hqgXeo/WRhgSbde1 3GOMVRznNWUQpWpM6oRymYxlQgfSmhokZzxHMaOud6hAHMI7hRSvRQgnpTP2D9VCRijV tvYOdRbm6MoDu4UgOmxt7sejA6CQywedGjOTRBl30ijbrDgQETYn5oZOqnGCtaAYcPZu MjsJRXAG04ApiH5Z6mU8Nc2C+hXCaIEB6zH7hUa5Up7nSwAgqcd3I/44d6H2f140ISuN zqINoaSTwBSBF/Nj+3hF7XpzbCbRiSR9QvteChaGaDG9beNmWGZas127F5+VFT8rM/v5 R54A== 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; bh=iuFA+HN3YQAhGF4lKe/pszwBtaIFpTgsToRqXaNjG7k=; b=u/uylYtf8O8l9e2tYsxOIICBD831cj0Mr+VuPREElkRd5WgHSt4F8SYUk43taoUBqm 0vSTrpSZhC9Bc4PxN78WIAz8MH3Y9qzpfpfV2c+oJ/2sdpmkgIEELxqzO4n2xCkOG4Kt f9pX/2h1/Olm45DVhet9v+r6PqxYNM26I/iByF+giiGixYkANadeaM5ZC7k/SvLFAS1s 4NNTlg9kg854xFrfc0Bx/OInt7QxNjl+SEzmkWETKCaWgVpJrdlxSl25VRLYYCw7d5P3 gubfo2DPo0bfcJH9lI70wFdTZcKMaM39+GRZuxlFcUeJZOvOP/HZ5ufd1TV4Jmsr272h N70Q== X-Gm-Message-State: ACgBeo0NILJutH+bdlTPj5U2pY1QBtiq0Cjd19jWeyhQrheZ1mCA6xyu hDKOwckSaMozu31SdJ1T0q6NgsQAx4g= X-Google-Smtp-Source: AA6agR67llFT6eQ0+3Cyyc4Z2yCAV5KwAp4HusV+mlw9qyUeJ6m9H2aBfcEzix7gu6JpzsX42cg/TQ27QPw= X-Received: from surenb-spec.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e30]) (user=surenb job=sendgmr) by 2002:a17:90a:e558:b0:1fb:c4b7:1a24 with SMTP id ei24-20020a17090ae55800b001fbc4b71a24mr21023pjb.1.1661808355887; Mon, 29 Aug 2022 14:25:55 -0700 (PDT) Date: Mon, 29 Aug 2022 21:25:14 +0000 In-Reply-To: <20220829212531.3184856-1-surenb@google.com> Mime-Version: 1.0 References: <20220829212531.3184856-1-surenb@google.com> X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220829212531.3184856-12-surenb@google.com> Subject: [RFC PATCH 11/28] mm/mmap: mark VMAs as locked before merging or splitting them 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, riel@surriel.com, 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, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, surenb@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Decisions about whether VMAs can be merged or split must be made while VMAs are protected from the changes which can affect that decision. For example, merge_vma uses vma->anon_vma in its decision whether the VMA can be merged. Meanwhile, page fault handler changes vma->anon_vma during COW operation. Mark all VMAs which might be affected by a merge or split operation as locked before making decision how such operations should be performed. Signed-off-by: Suren Baghdasaryan --- mm/mmap.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/mmap.c b/mm/mmap.c index ed58cf0689b2..ade3909c89b4 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1147,10 +1147,17 @@ struct vm_area_struct *vma_merge(struct mm_struct *= mm, if (vm_flags & VM_SPECIAL) return NULL; =20 + if (prev) + vma_mark_locked(prev); next =3D vma_next(mm, prev); area =3D next; - if (area && area->vm_end =3D=3D end) /* cases 6, 7, 8 */ + if (area) + vma_mark_locked(area); + if (area && area->vm_end =3D=3D end) { /* cases 6, 7, 8 */ next =3D next->vm_next; + if (next) + vma_mark_locked(next); + } =20 /* verify some invariant that must be enforced by the caller */ VM_WARN_ON(prev && addr <=3D prev->vm_start); @@ -2687,6 +2694,7 @@ int __split_vma(struct mm_struct *mm, struct vm_area_= struct *vma, struct vm_area_struct *new; int err; =20 + vma_mark_locked(vma); if (vma->vm_ops && vma->vm_ops->may_split) { err =3D vma->vm_ops->may_split(vma, addr); if (err) --=20 2.37.2.672.g94769d06f0-goog