From: Peter Xu <peterx@redhat.com>
To: Jerome Glisse <jglisse@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
David Hildenbrand <david@redhat.com>,
Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Martin Cracauer <cracauer@cons.org>, Shaohua Li <shli@fb.com>,
Marty McFadden <mcfadden8@llnl.gov>,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH v2 10/26] userfaultfd: wp: add UFFDIO_COPY_MODE_WP
Date: Mon, 25 Feb 2019 14:45:47 +0800 [thread overview]
Message-ID: <20190225064547.GB28121@xz-x1> (raw)
In-Reply-To: <20190222151546.GC7783@redhat.com>
On Fri, Feb 22, 2019 at 10:15:47AM -0500, Jerome Glisse wrote:
> On Fri, Feb 22, 2019 at 03:11:06PM +0800, Peter Xu wrote:
> > On Thu, Feb 21, 2019 at 12:29:19PM -0500, Jerome Glisse wrote:
> > > On Tue, Feb 12, 2019 at 10:56:16AM +0800, Peter Xu wrote:
> > > > From: Andrea Arcangeli <aarcange@redhat.com>
> > > >
> > > > This allows UFFDIO_COPY to map pages wrprotected.
> > > >
> > > > Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> > > > Signed-off-by: Peter Xu <peterx@redhat.com>
> > >
> > > Minor nitpick down below, but in any case:
> > >
> > > Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
> > >
> > > > ---
> > > > fs/userfaultfd.c | 5 +++--
> > > > include/linux/userfaultfd_k.h | 2 +-
> > > > include/uapi/linux/userfaultfd.h | 11 +++++-----
> > > > mm/userfaultfd.c | 36 ++++++++++++++++++++++----------
> > > > 4 files changed, 35 insertions(+), 19 deletions(-)
> > > >
> > >
> > > [...]
> > >
> > > > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> > > > index d59b5a73dfb3..73a208c5c1e7 100644
> > > > --- a/mm/userfaultfd.c
> > > > +++ b/mm/userfaultfd.c
> > > > @@ -25,7 +25,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
> > > > struct vm_area_struct *dst_vma,
> > > > unsigned long dst_addr,
> > > > unsigned long src_addr,
> > > > - struct page **pagep)
> > > > + struct page **pagep,
> > > > + bool wp_copy)
> > > > {
> > > > struct mem_cgroup *memcg;
> > > > pte_t _dst_pte, *dst_pte;
> > > > @@ -71,9 +72,9 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
> > > > if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false))
> > > > goto out_release;
> > > >
> > > > - _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
> > > > - if (dst_vma->vm_flags & VM_WRITE)
> > > > - _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
> > > > + _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot));
> > > > + if (dst_vma->vm_flags & VM_WRITE && !wp_copy)
> > > > + _dst_pte = pte_mkwrite(_dst_pte);
> > >
> > > I like parenthesis around around and :) ie:
> > > (dst_vma->vm_flags & VM_WRITE) && !wp_copy
> > >
> > > I feel it is easier to read.
> >
> > Yeah another one. Though this line will be changed in follow up
> > patches, will fix anyways.
> >
> > >
> > > [...]
> > >
> > > > @@ -416,11 +418,13 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
> > > > if (!(dst_vma->vm_flags & VM_SHARED)) {
> > > > if (!zeropage)
> > > > err = mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma,
> > > > - dst_addr, src_addr, page);
> > > > + dst_addr, src_addr, page,
> > > > + wp_copy);
> > > > else
> > > > err = mfill_zeropage_pte(dst_mm, dst_pmd,
> > > > dst_vma, dst_addr);
> > > > } else {
> > > > + VM_WARN_ON(wp_copy); /* WP only available for anon */
> > >
> > > Don't you want to return with error here ?
> >
> > Makes sense to me. Does this looks good to you to be squashed into
> > current patch?
> >
> > diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> > index 73a208c5c1e7..f3ea09f412d4 100644
> > --- a/mm/userfaultfd.c
> > +++ b/mm/userfaultfd.c
> > @@ -73,7 +73,7 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm,
> > goto out_release;
> >
> > _dst_pte = pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot));
> > - if (dst_vma->vm_flags & VM_WRITE && !wp_copy)
> > + if ((dst_vma->vm_flags & VM_WRITE) && !wp_copy)
> > _dst_pte = pte_mkwrite(_dst_pte);
> >
> > dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
> > @@ -424,7 +424,10 @@ static __always_inline ssize_t mfill_atomic_pte(struct mm_struct *dst_mm,
> > err = mfill_zeropage_pte(dst_mm, dst_pmd,
> > dst_vma, dst_addr);
> > } else {
> > - VM_WARN_ON(wp_copy); /* WP only available for anon */
> > + if (unlikely(wp_copy))
> > + /* TODO: WP currently only available for anon */
> > + return -EINVAL;
> > +
> > if (!zeropage)
> > err = shmem_mcopy_atomic_pte(dst_mm, dst_pmd,
> > dst_vma, dst_addr,
>
> I would keep a the VM_WARN_ON or maybe a ONCE variant so that we at
> least have a chance to be inform if for some reasons that code path
> is taken. With that my r-b stands.
Yeah *ONCE() is good to me too (both can avoid DOS attack from
userspace) and I don't have strong opinion on whether we should fail
on this specific ioctl if it happens. For now I'll just take the
advise and the r-b together. Thanks,
--
Peter Xu
next prev parent reply other threads:[~2019-02-25 6:46 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-12 2:56 [PATCH v2 00/26] userfaultfd: write protection support Peter Xu
2019-02-12 2:56 ` [PATCH v2 01/26] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-02-21 15:17 ` Jerome Glisse
2019-02-22 3:42 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 02/26] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-02-21 15:29 ` Jerome Glisse
2019-02-22 3:51 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 03/26] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-02-21 15:34 ` Jerome Glisse
2019-02-12 2:56 ` [PATCH v2 04/26] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-02-13 3:34 ` Peter Xu
2019-02-20 11:48 ` Peter Xu
2019-02-21 8:56 ` [PATCH v2.1 " Peter Xu
2019-02-21 15:53 ` Jerome Glisse
2019-02-22 4:25 ` Peter Xu
2019-02-22 15:11 ` Jerome Glisse
2019-02-25 6:19 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 05/26] mm: gup: " Peter Xu
2019-02-21 16:06 ` Jerome Glisse
2019-02-22 4:41 ` Peter Xu
2019-02-22 15:13 ` Jerome Glisse
2019-02-12 2:56 ` [PATCH v2 06/26] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-02-21 16:07 ` Jerome Glisse
2019-02-25 15:41 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 07/26] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-02-21 16:25 ` Jerome Glisse
2019-02-25 15:43 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 08/26] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-02-21 17:20 ` Jerome Glisse
2019-02-25 15:48 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 09/26] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-02-21 17:21 ` Jerome Glisse
2019-02-25 17:12 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 10/26] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-02-21 17:29 ` Jerome Glisse
2019-02-22 7:11 ` Peter Xu
2019-02-22 15:15 ` Jerome Glisse
2019-02-25 6:45 ` Peter Xu [this message]
2019-02-25 15:58 ` Mike Rapoport
2019-02-26 5:09 ` Peter Xu
2019-02-26 8:28 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 11/26] mm: merge parameters for change_protection() Peter Xu
2019-02-21 17:32 ` Jerome Glisse
2019-02-12 2:56 ` [PATCH v2 12/26] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-02-21 17:44 ` Jerome Glisse
2019-02-22 7:31 ` Peter Xu
2019-02-22 15:17 ` Jerome Glisse
2019-02-25 18:00 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 13/26] mm: export wp_page_copy() Peter Xu
2019-02-21 17:44 ` Jerome Glisse
2019-02-12 2:56 ` [PATCH v2 14/26] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-02-21 18:04 ` Jerome Glisse
2019-02-22 8:46 ` Peter Xu
2019-02-22 15:35 ` Jerome Glisse
2019-02-25 7:13 ` Peter Xu
2019-02-25 15:32 ` Jerome Glisse
2019-02-12 2:56 ` [PATCH v2 15/26] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-02-21 18:06 ` Jerome Glisse
2019-02-22 9:09 ` Peter Xu
2019-02-22 15:36 ` Jerome Glisse
2019-02-25 18:19 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 16/26] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-02-21 18:07 ` Jerome Glisse
2019-02-25 18:20 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 17/26] userfaultfd: wp: support swap and page migration Peter Xu
2019-02-21 18:16 ` Jerome Glisse
2019-02-25 7:48 ` Peter Xu
2019-02-25 18:28 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 18/26] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-02-21 18:17 ` Jerome Glisse
2019-02-25 18:50 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 19/26] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-02-21 18:19 ` Jerome Glisse
2019-02-25 20:48 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 20/26] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-02-21 18:23 ` Jerome Glisse
2019-02-25 8:16 ` Peter Xu
2019-02-25 20:52 ` Mike Rapoport
2019-02-26 6:06 ` Peter Xu
2019-02-26 6:43 ` Mike Rapoport
2019-02-26 7:20 ` Peter Xu
2019-02-26 7:46 ` Mike Rapoport
2019-02-26 7:54 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 21/26] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-02-21 18:28 ` Jerome Glisse
2019-02-25 8:31 ` Peter Xu
2019-02-25 21:03 ` Mike Rapoport
2019-02-26 6:30 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 22/26] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-02-21 18:29 ` Jerome Glisse
2019-02-25 8:34 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 23/26] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-02-21 18:36 ` Jerome Glisse
2019-02-25 8:58 ` Peter Xu
2019-02-25 21:15 ` Mike Rapoport
2019-02-25 21:09 ` Mike Rapoport
2019-02-26 6:24 ` Peter Xu
2019-02-26 7:29 ` Mike Rapoport
2019-02-26 7:41 ` Peter Xu
2019-02-26 8:00 ` Mike Rapoport
2019-02-28 2:47 ` Peter Xu
2019-02-26 8:00 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 24/26] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-02-21 18:38 ` Jerome Glisse
2019-02-25 21:19 ` Mike Rapoport
2019-02-26 6:53 ` Peter Xu
2019-02-26 7:04 ` Mike Rapoport
2019-02-26 7:42 ` Peter Xu
2019-02-12 2:56 ` [PATCH v2 25/26] userfaultfd: selftests: refactor statistics Peter Xu
2019-02-26 6:50 ` Mike Rapoport
2019-02-12 2:56 ` [PATCH v2 26/26] userfaultfd: selftests: add write-protect test Peter Xu
2019-02-26 6:58 ` Mike Rapoport
2019-02-26 7:52 ` Peter Xu
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