From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7F2A6C433DB for ; Mon, 28 Dec 2020 18:04:29 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 02EC222AAD for ; Mon, 28 Dec 2020 18:04:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 02EC222AAD Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 40E938D0015; Mon, 28 Dec 2020 13:04:28 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3E53D8D0010; Mon, 28 Dec 2020 13:04:28 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 25E838D0017; Mon, 28 Dec 2020 13:04:28 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0247.hostedemail.com [216.40.44.247]) by kanga.kvack.org (Postfix) with ESMTP id 0B1CE8D0010 for ; Mon, 28 Dec 2020 13:04:28 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A2377181AEF07 for ; Mon, 28 Dec 2020 18:04:27 +0000 (UTC) X-FDA: 77643465774.20.pest39_2600c3927495 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id 7C1C6180C0609 for ; Mon, 28 Dec 2020 18:04:27 +0000 (UTC) X-HE-Tag: pest39_2600c3927495 X-Filterd-Recvd-Size: 7716 Received: from mail-ed1-f52.google.com (mail-ed1-f52.google.com [209.85.208.52]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Mon, 28 Dec 2020 18:04:26 +0000 (UTC) Received: by mail-ed1-f52.google.com with SMTP id c7so10479764edv.6 for ; Mon, 28 Dec 2020 10:04:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=1XusoXZzXCem561CtyIdzy62jFmYgYhqvsSbO2ZR46c=; b=DSVHc07QIUtK0soe718/PW/vZrg/PwxdrGhBs/wdvz/6NZ5gelqZ4YnCbT352WJC91 dh5awmqXzc0qxiZ24nUdgL0rUgk8LcHGFH4YsnmFRABICxIhpHib1j1md3bk8M2WX+7G cJgZESQWMXQESYa91RJzUhAxego4Q8a/mqJvQdMQy1tv/+pr4hdGZXtfHNted17QO6qV EKNdTEwowdGP5ptmy3jCYCCyGGxx+K9GoOdZ5jIC3tC1Ek/H8wIv7ryHuemAtUfsQSYP DucXlyVr0d8JhcPmnQHqv231RHMAgr6XkW72K23FCLd296Ym7zAhF7bkFrRSPqYiondR Uhsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=1XusoXZzXCem561CtyIdzy62jFmYgYhqvsSbO2ZR46c=; b=QdRMX6apGxeAhQ10oEAv+b81F+6GSykMszurhjpu/aA/ds6S/SLyBpEJu+KuaOyBEh 5yxIuwaMWnlbrSMPN/D2bdezv8lUllbuk7m4eDCAENIQkK2my/Yi/17XhWlLCO0tVYGI Rb0/3euXnupR80471OcWH08dGm+0aStmQ2dhfyWF21m/ECDlwoFrQb5BiZVfnZ/6BAzk P7DKIBY3yaYizRL5TpA1S1NBPfUiEDJWBnx1jJIqkH9pJcRdTMa2YBDNerG1auM78+yS /m74fT63mL/9uxK5b+zCSX3+epzLdDG+OA8kvAVY8ic9zL8lY4dnyjT9Sf9QLZ9pCVE/ ot2Q== X-Gm-Message-State: AOAM5305/SaYUUx2WVnD2mt6Vrt046nPoTfqg7yNDax2qL5x9MWpyco1 e5GiI9v3JOnbsYJ50t5yVIdiKqfomYI/juFjDQUXwQ== X-Google-Smtp-Source: ABdhPJyEbHA18+GopoW3MrvxLDasfYjKRSDmjFduYaqBmPBoPByVJC0UFsKLtmKZ0K20lohnh4X0Ekjt12pIRB8mL3o= X-Received: by 2002:a50:fd18:: with SMTP id i24mr43835414eds.146.1609178665726; Mon, 28 Dec 2020 10:04:25 -0800 (PST) MIME-Version: 1.0 References: <20201013013416.390574-1-dima@arista.com> <20201013013416.390574-4-dima@arista.com> In-Reply-To: <20201013013416.390574-4-dima@arista.com> From: Brian Geffon Date: Mon, 28 Dec 2020 10:03:49 -0800 Message-ID: Subject: Re: [PATCH 3/6] mremap: Don't allow MREMAP_DONTUNMAP on special_mappings and aio To: Dmitry Safonov Cc: LKML , Dmitry Safonov <0x7f454c46@gmail.com>, Alexander Viro , Andrew Morton , Andy Lutomirski , Catalin Marinas , Dan Williams , Dave Jiang , Hugh Dickins , Ingo Molnar , "Kirill A. Shutemov" , Mike Kravetz , Minchan Kim , Russell King , Thomas Bogendoerfer , Thomas Gleixner , Vishal Verma , Vlastimil Babka , Will Deacon , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-mm Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: I don't think this situation can ever happen MREMAP_DONTUNMAP is already restricted to anonymous mappings (defined as not having vm_ops) and vma_to_resize checks that the mapping is anonymous before move_vma is called. On Mon, Oct 12, 2020 at 6:34 PM Dmitry Safonov wrote: > > As kernel expect to see only one of such mappings, any further > operations on the VMA-copy may be unexpected by the kernel. > Maybe it's being on the safe side, but there doesn't seem to be any > expected use-case for this, so restrict it now. > > Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") > Signed-off-by: Dmitry Safonov > --- > arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 2 +- > fs/aio.c | 5 ++++- > include/linux/mm.h | 2 +- > mm/mmap.c | 6 +++++- > mm/mremap.c | 2 +- > 5 files changed, 12 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c > index 0daf2f1cf7a8..e916646adc69 100644 > --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c > +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c > @@ -1458,7 +1458,7 @@ static int pseudo_lock_dev_release(struct inode *inode, struct file *filp) > return 0; > } > > -static int pseudo_lock_dev_mremap(struct vm_area_struct *area) > +static int pseudo_lock_dev_mremap(struct vm_area_struct *area, unsigned long flags) > { > /* Not supported */ > return -EINVAL; > diff --git a/fs/aio.c b/fs/aio.c > index d5ec30385566..3be3c0f77548 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -324,13 +324,16 @@ static void aio_free_ring(struct kioctx *ctx) > } > } > > -static int aio_ring_mremap(struct vm_area_struct *vma) > +static int aio_ring_mremap(struct vm_area_struct *vma, unsigned long flags) > { > struct file *file = vma->vm_file; > struct mm_struct *mm = vma->vm_mm; > struct kioctx_table *table; > int i, res = -EINVAL; > > + if (flags & MREMAP_DONTUNMAP) > + return -EINVAL; > + > spin_lock(&mm->ioctx_lock); > rcu_read_lock(); > table = rcu_dereference(mm->ioctx_table); > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 16b799a0522c..fd51a4a1f722 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -550,7 +550,7 @@ struct vm_operations_struct { > void (*open)(struct vm_area_struct * area); > void (*close)(struct vm_area_struct * area); > int (*split)(struct vm_area_struct * area, unsigned long addr); > - int (*mremap)(struct vm_area_struct * area); > + int (*mremap)(struct vm_area_struct *area, unsigned long flags); > vm_fault_t (*fault)(struct vm_fault *vmf); > vm_fault_t (*huge_fault)(struct vm_fault *vmf, > enum page_entry_size pe_size); > diff --git a/mm/mmap.c b/mm/mmap.c > index bdd19f5b994e..50f853b0ec39 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -3372,10 +3372,14 @@ static const char *special_mapping_name(struct vm_area_struct *vma) > return ((struct vm_special_mapping *)vma->vm_private_data)->name; > } > > -static int special_mapping_mremap(struct vm_area_struct *new_vma) > +static int special_mapping_mremap(struct vm_area_struct *new_vma, > + unsigned long flags) > { > struct vm_special_mapping *sm = new_vma->vm_private_data; > > + if (flags & MREMAP_DONTUNMAP) > + return -EINVAL; > + > if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) > return -EFAULT; > > diff --git a/mm/mremap.c b/mm/mremap.c > index c248f9a52125..898e9818ba6d 100644 > --- a/mm/mremap.c > +++ b/mm/mremap.c > @@ -384,7 +384,7 @@ static unsigned long move_vma(struct vm_area_struct *vma, > if (moved_len < old_len) { > err = -ENOMEM; > } else if (vma->vm_ops && vma->vm_ops->mremap) { > - err = vma->vm_ops->mremap(new_vma); > + err = vma->vm_ops->mremap(new_vma, flags); > } > > if (unlikely(err)) { > -- > 2.28.0 >