From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: David Hildenbrand <david@redhat.com>,
Hugh Dickins <hughd@google.com>, Maya Gokhale <gokhale2@llnl.gov>,
Jerome Glisse <jglisse@redhat.com>,
Pavel Emelyanov <xemul@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
peterx@redhat.com, Martin Cracauer <cracauer@cons.org>,
Shaohua Li <shli@fb.com>, Andrea Arcangeli <aarcange@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Denis Plotnikov <dplotnikov@virtuozzo.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Marty McFadden <mcfadden8@llnl.gov>, Mel Gorman <mgorman@suse.de>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v3 25/28] userfaultfd: wp: fixup swap entries in change_pte_range
Date: Wed, 20 Mar 2019 10:06:39 +0800 [thread overview]
Message-ID: <20190320020642.4000-26-peterx@redhat.com> (raw)
In-Reply-To: <20190320020642.4000-1-peterx@redhat.com>
In change_pte_range() we do nothing for uffd if the PTE is a swap
entry. That can lead to data mismatch if the page that we are going
to write protect is swapped out when sending the UFFDIO_WRITEPROTECT.
This patch applies/removes the uffd-wp bit even for the swap entries.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
I kept this patch a standalone one majorly to make review easier. The
patch can be considered as standalone or to squash into the patch
"userfaultfd: wp: support swap and page migration".
---
mm/mprotect.c | 24 +++++++++++++-----------
1 file changed, 13 insertions(+), 11 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 96c0f521099d..a23e03053787 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -183,11 +183,11 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
}
ptep_modify_prot_commit(mm, addr, pte, ptent);
pages++;
- } else if (IS_ENABLED(CONFIG_MIGRATION)) {
+ } else if (is_swap_pte(oldpte)) {
swp_entry_t entry = pte_to_swp_entry(oldpte);
+ pte_t newpte;
if (is_write_migration_entry(entry)) {
- pte_t newpte;
/*
* A protection check is difficult so
* just be safe and disable write
@@ -198,22 +198,24 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
newpte = pte_swp_mksoft_dirty(newpte);
if (pte_swp_uffd_wp(oldpte))
newpte = pte_swp_mkuffd_wp(newpte);
- set_pte_at(mm, addr, pte, newpte);
-
- pages++;
- }
-
- if (is_write_device_private_entry(entry)) {
- pte_t newpte;
-
+ } else if (is_write_device_private_entry(entry)) {
/*
* We do not preserve soft-dirtiness. See
* copy_one_pte() for explanation.
*/
make_device_private_entry_read(&entry);
newpte = swp_entry_to_pte(entry);
- set_pte_at(mm, addr, pte, newpte);
+ } else {
+ newpte = oldpte;
+ }
+ if (uffd_wp)
+ newpte = pte_swp_mkuffd_wp(newpte);
+ else if (uffd_wp_resolve)
+ newpte = pte_swp_clear_uffd_wp(newpte);
+
+ if (!pte_same(oldpte, newpte)) {
+ set_pte_at(mm, addr, pte, newpte);
pages++;
}
}
--
2.17.1
next prev parent reply other threads:[~2019-03-20 2:10 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-20 2:06 [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-03-20 2:06 ` [PATCH v3 01/28] mm: gup: rename "nonblocking" to "locked" where proper Peter Xu
2019-03-20 2:06 ` [PATCH v3 02/28] mm: userfault: return VM_FAULT_RETRY on signals Peter Xu
2019-03-20 2:06 ` [PATCH v3 03/28] userfaultfd: don't retake mmap_sem to emulate NOPAGE Peter Xu
2019-03-20 2:06 ` [PATCH v3 04/28] mm: allow VM_FAULT_RETRY for multiple times Peter Xu
2019-04-18 20:11 ` Jerome Glisse
2019-04-19 6:00 ` Peter Xu
2019-03-20 2:06 ` [PATCH v3 05/28] mm: gup: " Peter Xu
2019-03-20 2:06 ` [PATCH v3 06/28] userfaultfd: wp: add helper for writeprotect check Peter Xu
2019-03-20 2:06 ` [PATCH v3 07/28] userfaultfd: wp: hook userfault handler to write protection fault Peter Xu
2019-04-18 20:03 ` Jerome Glisse
2019-03-20 2:06 ` [PATCH v3 08/28] userfaultfd: wp: add WP pagetable tracking to x86 Peter Xu
2019-03-20 2:06 ` [PATCH v3 09/28] userfaultfd: wp: userfaultfd_pte/huge_pmd_wp() helpers Peter Xu
2019-03-20 2:06 ` [PATCH v3 10/28] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Peter Xu
2019-03-20 2:06 ` [PATCH v3 11/28] mm: merge parameters for change_protection() Peter Xu
2019-03-20 2:06 ` [PATCH v3 12/28] userfaultfd: wp: apply _PAGE_UFFD_WP bit Peter Xu
2019-03-20 2:06 ` [PATCH v3 13/28] mm: export wp_page_copy() Peter Xu
2019-03-20 2:06 ` [PATCH v3 14/28] userfaultfd: wp: handle COW properly for uffd-wp Peter Xu
2019-04-18 20:51 ` Jerome Glisse
2019-04-19 6:26 ` Peter Xu
2019-04-19 15:02 ` Jerome Glisse
2019-04-22 12:20 ` Peter Xu
2019-04-22 14:54 ` Jerome Glisse
2019-04-23 3:00 ` Peter Xu
2019-04-23 15:34 ` Jerome Glisse
2019-04-24 8:38 ` Peter Xu
2019-03-20 2:06 ` [PATCH v3 15/28] userfaultfd: wp: drop _PAGE_UFFD_WP properly when fork Peter Xu
2019-03-20 2:06 ` [PATCH v3 16/28] userfaultfd: wp: add pmd_swp_*uffd_wp() helpers Peter Xu
2019-03-20 2:06 ` [PATCH v3 17/28] userfaultfd: wp: support swap and page migration Peter Xu
2019-04-18 20:59 ` Jerome Glisse
2019-04-19 7:42 ` Peter Xu
2019-04-19 15:08 ` Jerome Glisse
2019-04-22 12:23 ` Peter Xu
2019-03-20 2:06 ` [PATCH v3 18/28] khugepaged: skip collapse if uffd-wp detected Peter Xu
2019-03-20 2:06 ` [PATCH v3 19/28] userfaultfd: introduce helper vma_find_uffd Peter Xu
2019-03-20 2:06 ` [PATCH v3 20/28] userfaultfd: wp: support write protection for userfault vma range Peter Xu
2019-03-20 2:06 ` [PATCH v3 21/28] userfaultfd: wp: add the writeprotect API to userfaultfd ioctl Peter Xu
2019-03-20 2:06 ` [PATCH v3 22/28] userfaultfd: wp: enabled write protection in userfaultfd API Peter Xu
2019-03-22 21:37 ` Mike Rapoport
2019-03-20 2:06 ` [PATCH v3 23/28] userfaultfd: wp: don't wake up when doing write protect Peter Xu
2019-03-20 2:06 ` [PATCH v3 24/28] userfaultfd: wp: UFFDIO_REGISTER_MODE_WP documentation update Peter Xu
2019-03-22 21:46 ` Mike Rapoport
2019-03-20 2:06 ` Peter Xu [this message]
2019-04-18 21:01 ` [PATCH v3 25/28] userfaultfd: wp: fixup swap entries in change_pte_range Jerome Glisse
2019-03-20 2:06 ` [PATCH v3 26/28] userfaultfd: wp: declare _UFFDIO_WRITEPROTECT conditionally Peter Xu
2019-03-22 21:43 ` Mike Rapoport
2019-03-20 2:06 ` [PATCH v3 27/28] userfaultfd: selftests: refactor statistics Peter Xu
2019-03-20 2:06 ` [PATCH v3 28/28] userfaultfd: selftests: add write-protect test Peter Xu
2019-04-09 6:08 ` [PATCH v3 00/28] userfaultfd: write protection support Peter Xu
2019-04-18 21:07 ` Jerome Glisse
2019-04-19 7:53 ` Peter Xu
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