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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 25 Feb 2019 18:19:57 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x1PIJuHh31129848 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 25 Feb 2019 18:19:56 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6F55D11C052; Mon, 25 Feb 2019 18:19:56 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 67EF411C05C; Mon, 25 Feb 2019 18:19:52 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.205.26]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Mon, 25 Feb 2019 18:19:52 +0000 (GMT) Date: Mon, 25 Feb 2019 20:19:49 +0200 From: Mike Rapoport To: Peter Xu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, David Hildenbrand , Hugh Dickins , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Shaohua Li , Marty McFadden , Andrea Arcangeli , Mike Kravetz , Denis Plotnikov , Mike Rapoport , Mel Gorman , "Kirill A . Shutemov" , "Dr . David Alan Gilbert" Subject: Re: [PATCH v2 15/26] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork References: <20190212025632.28946-1-peterx@redhat.com> <20190212025632.28946-16-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190212025632.28946-16-peterx@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19022518-4275-0000-0000-00000313CC8D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19022518-4276-0000-0000-0000382209B5 Message-Id: <20190225181947.GG24917@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-25_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902250133 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 12, 2019 at 10:56:21AM +0800, Peter Xu wrote: > UFFD_EVENT_FORK support for uffd-wp should be already there, except > that we should clean the uffd-wp bit if uffd fork event is not > enabled. Detect that to avoid _PAGE_UFFD_WP being set even if the VMA > is not being tracked by VM_UFFD_WP. Do this for both small PTEs and > huge PMDs. > > Signed-off-by: Peter Xu Reviewed-by: Mike Rapoport > --- > mm/huge_memory.c | 8 ++++++++ > mm/memory.c | 8 ++++++++ > 2 files changed, 16 insertions(+) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 817335b443c2..fb2234cb595a 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -938,6 +938,14 @@ int copy_huge_pmd(struct mm_struct *dst_mm, struct mm_struct *src_mm, > ret = -EAGAIN; > pmd = *src_pmd; > > + /* > + * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA > + * does not have the VM_UFFD_WP, which means that the uffd > + * fork event is not enabled. > + */ > + if (!(vma->vm_flags & VM_UFFD_WP)) > + pmd = pmd_clear_uffd_wp(pmd); > + > #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION > if (unlikely(is_swap_pmd(pmd))) { > swp_entry_t entry = pmd_to_swp_entry(pmd); > diff --git a/mm/memory.c b/mm/memory.c > index b5d67bafae35..c2035539e9fd 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -788,6 +788,14 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, > pte = pte_mkclean(pte); > pte = pte_mkold(pte); > > + /* > + * Make sure the _PAGE_UFFD_WP bit is cleared if the new VMA > + * does not have the VM_UFFD_WP, which means that the uffd > + * fork event is not enabled. > + */ > + if (!(vm_flags & VM_UFFD_WP)) > + pte = pte_clear_uffd_wp(pte); > + > page = vm_normal_page(vma, addr, pte); > if (page) { > get_page(page); > -- > 2.17.1 > -- Sincerely yours, Mike.