From nobody Mon Apr 6 23:13:09 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 617C9ECAAD1 for ; Thu, 1 Sep 2022 17:37:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234959AbiIARhG (ORCPT ); Thu, 1 Sep 2022 13:37:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234343AbiIARgC (ORCPT ); Thu, 1 Sep 2022 13:36:02 -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 6BF2685F89 for ; Thu, 1 Sep 2022 10:35:51 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-340ae84fb7dso202788047b3.17 for ; Thu, 01 Sep 2022 10:35:51 -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:subject:date; bh=IUrOZBQLzZPUHaSf75EcaCRmzwc/1Uln8Bhr3CCRW40=; b=RqTxEDKmKz8lQ9e4qoEc4uYxV2l6ZaYMJyNDEM2PccdKcjIk6CnRCwBsEF2cj3JFvG j1vM9+I5MFJ8Y28kW9pfnzwXL/sLYGBlEyABKHcApM/RmMkSzapOCNpQMv7qth5lMe9Z r4q/GOZemPIxyE1pZ9TWp0QmyjLs2nHHEkPOAyS+5ktrUUhx4EO8hL8MjHB9ieBIjUIm Yg7XSf+rAL+v2NSP5NDXERvFs20Phv4/bhur7fMLyFA6L2AN5XBQFKbc4pQ3AuRWkJ+n hhBQmROSc08GaGFWWbM/WsNha74+z1T1INvujKYoiSdnjlDI7QzZLxl1fThOa82IPdUF 4lpQ== 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; bh=IUrOZBQLzZPUHaSf75EcaCRmzwc/1Uln8Bhr3CCRW40=; b=4SuKl4rV9Gh3ZTRZQaLRao/8FA/e97RULa5AOKfbfBUIpANlzIaYV9O6NaT53StVuK lvCUph7fR1cP0hBQ7Ob9LAjrYZRJFBL1ROV0tvtHXpmm15x5MHC3U2R+yd1nQQpMH+xo ZVwqVb/2LlQD0H+hX5IUliBJTLmG3P1nmsX6rvDhxJ2sLdawKIJkNSVH8nfW6qIV3oQi 73nwBp61XYm0kP1ksNgNUEUtPULa/jjRVWAFNxTcgp33Am/f5twbAkiI8QzAXgycfCYK ZrSKVLjqk/bGGSPgVzXRhgXJaUQrlqro+dZBzQ314VKauMbJa0wEmFNo45PDt62NDk52 y+fQ== X-Gm-Message-State: ACgBeo04PrR3BI2Jml1aCX1sHSFie3A7dFA04SaP8zbXGqpX7ph94t92 41QKm0IDYi+oDl6RXEWn4jLdSZ+gxTo= X-Google-Smtp-Source: AA6agR7hyHeb8khg+/3ZoJp3oFVauMFyBSatbGnIGl1CpSfGDYZylUwLzf/LZXvggze+7Aght5uln8kJbB0= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:1bfc:e7ee:6530:4449]) (user=surenb job=sendgmr) by 2002:a0d:e083:0:b0:343:2928:867f with SMTP id j125-20020a0de083000000b003432928867fmr6902464ywe.467.1662053750534; Thu, 01 Sep 2022 10:35:50 -0700 (PDT) Date: Thu, 1 Sep 2022 10:34:59 -0700 In-Reply-To: <20220901173516.702122-1-surenb@google.com> Mime-Version: 1.0 References: <20220901173516.702122-1-surenb@google.com> X-Mailer: git-send-email 2.37.2.789.g6183377224-goog Message-ID: <20220901173516.702122-12-surenb@google.com> Subject: [RFC PATCH RESEND 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@suse.de, 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, 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 Reviewed-by: Laurent Dufour --- 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 2.37.2.789.g6183377224-goog