From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
David Hildenbrand <david@redhat.com>,
Hugh Dickins <hughd@google.com>,
Jerome Glisse <jglisse@redhat.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Alistair Popple <apopple@nvidia.com>,
peterx@redhat.com
Subject: [PATCH v8 09/23] mm/shmem: Allows file-back mem to be uffd wr-protected on thps
Date: Mon, 4 Apr 2022 21:48:52 -0400 [thread overview]
Message-ID: <20220405014852.14413-1-peterx@redhat.com> (raw)
In-Reply-To: <20220405014646.13522-1-peterx@redhat.com>
We don't have "huge" version of pte markers, instead when necessary we split
the thp.
However split the thp is not enough, because file-backed thp is handled totally
differently comparing to anonymous thps: rather than doing a real split, the
thp pmd will simply got cleared in __split_huge_pmd_locked().
That is not enough if e.g. when there is a thp covers range [0, 2M) but we want
to wr-protect small page resides in [4K, 8K) range, because after
__split_huge_pmd() returns, there will be a none pmd, and change_pmd_range()
will just skip it right after the split.
Here we leverage the previously introduced change_pmd_prepare() macro so that
we'll populate the pmd with a pgtable page after the pmd split (in which
process the pmd will be cleared for cases like shmem). Then change_pte_range()
will do all the rest for us by installing the uffd-wp pte marker at any none
pte that we'd like to wr-protect.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/mprotect.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c
index bd62d5938c6c..e0a567b66d07 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -333,8 +333,15 @@ static inline unsigned long change_pmd_range(struct vm_area_struct *vma,
}
if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
- if (next - addr != HPAGE_PMD_SIZE) {
+ if ((next - addr != HPAGE_PMD_SIZE) ||
+ uffd_wp_protect_file(vma, cp_flags)) {
__split_huge_pmd(vma, pmd, addr, false, NULL);
+ /*
+ * For file-backed, the pmd could have been
+ * cleared; make sure pmd populated if
+ * necessary, then fall-through to pte level.
+ */
+ change_pmd_prepare(vma, pmd, cp_flags);
} else {
int nr_ptes = change_huge_pmd(vma, pmd, addr,
newprot, cp_flags);
--
2.32.0
next prev parent reply other threads:[~2022-04-05 2:42 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-05 1:46 [PATCH v8 00/23] userfaultfd-wp: Support shmem and hugetlbfs Peter Xu
2022-04-05 1:46 ` [PATCH v8 01/23] mm: Introduce PTE_MARKER swap entry Peter Xu
2022-04-12 1:07 ` Alistair Popple
2022-04-12 19:45 ` Peter Xu
2022-04-13 0:30 ` Alistair Popple
2022-04-13 13:44 ` Peter Xu
2022-04-19 8:25 ` Alistair Popple
2022-04-19 19:44 ` Peter Xu
2022-04-05 1:48 ` [PATCH v8 02/23] mm: Teach core mm about pte markers Peter Xu
2022-04-12 1:22 ` Alistair Popple
2022-04-12 19:53 ` Peter Xu
2022-04-05 1:48 ` [PATCH v8 03/23] mm: Check against orig_pte for finish_fault() Peter Xu
2022-04-12 2:05 ` Alistair Popple
2022-04-12 19:54 ` Peter Xu
[not found] ` <CGME20220413140330eucas1p167da41e079712b829ef8237dc27b049c@eucas1p1.samsung.com>
2022-04-13 14:03 ` Marek Szyprowski
2022-04-13 16:43 ` Peter Xu
2022-04-14 7:51 ` Marek Szyprowski
2022-04-14 16:30 ` Peter Xu
2022-04-14 20:57 ` Andrew Morton
2022-04-14 21:08 ` Peter Xu
2022-04-15 14:21 ` Guenter Roeck
2022-04-15 14:41 ` Peter Xu
2022-04-05 1:48 ` [PATCH v8 04/23] mm/uffd: PTE_MARKER_UFFD_WP Peter Xu
2022-04-06 1:41 ` kernel test robot
2022-04-05 1:48 ` [PATCH v8 05/23] mm/shmem: Take care of UFFDIO_COPY_MODE_WP Peter Xu
2022-04-05 1:48 ` [PATCH v8 06/23] mm/shmem: Handle uffd-wp special pte in page fault handler Peter Xu
2022-05-11 16:30 ` David Hildenbrand
2022-05-12 16:34 ` Peter Xu
2022-04-05 1:48 ` [PATCH v8 07/23] mm/shmem: Persist uffd-wp bit across zapping for file-backed Peter Xu
2022-04-05 1:48 ` [PATCH v8 08/23] mm/shmem: Allow uffd wr-protect none pte for file-backed mem Peter Xu
2022-04-05 1:48 ` Peter Xu [this message]
2022-04-05 1:48 ` [PATCH v8 10/23] mm/shmem: Handle uffd-wp during fork() Peter Xu
2022-04-06 6:16 ` kernel test robot
2022-04-06 12:18 ` Peter Xu
2022-04-05 1:48 ` [PATCH v8 11/23] mm/hugetlb: Introduce huge pte version of uffd-wp helpers Peter Xu
2022-04-05 1:49 ` [PATCH v8 12/23] mm/hugetlb: Hook page faults for uffd write protection Peter Xu
2022-04-05 1:49 ` [PATCH v8 13/23] mm/hugetlb: Take care of UFFDIO_COPY_MODE_WP Peter Xu
2022-04-05 1:49 ` [PATCH v8 14/23] mm/hugetlb: Handle UFFDIO_WRITEPROTECT Peter Xu
2022-04-05 1:49 ` [PATCH v8 15/23] mm/hugetlb: Handle pte markers in page faults Peter Xu
2022-04-06 13:37 ` kernel test robot
2022-04-06 15:02 ` Peter Xu
2022-04-05 1:49 ` [PATCH v8 16/23] mm/hugetlb: Allow uffd wr-protect none ptes Peter Xu
2022-04-05 1:49 ` [PATCH v8 17/23] mm/hugetlb: Only drop uffd-wp special pte if required Peter Xu
2022-04-05 1:49 ` [PATCH v8 18/23] mm/hugetlb: Handle uffd-wp during fork() Peter Xu
2022-04-05 1:49 ` [PATCH v8 19/23] mm/khugepaged: Don't recycle vma pgtable if uffd-wp registered Peter Xu
2022-04-05 1:49 ` [PATCH v8 20/23] mm/pagemap: Recognize uffd-wp bit for shmem/hugetlbfs Peter Xu
2022-04-05 1:49 ` [PATCH v8 21/23] mm/uffd: Enable write protection for shmem & hugetlbfs Peter Xu
2022-04-05 1:49 ` [PATCH v8 22/23] mm: Enable PTE markers by default Peter Xu
2022-04-19 15:13 ` Johannes Weiner
2022-04-19 19:59 ` Peter Xu
2022-04-19 20:14 ` Johannes Weiner
2022-04-19 20:28 ` Peter Xu
2022-04-19 21:24 ` Johannes Weiner
2022-04-19 22:01 ` Peter Xu
2022-04-20 13:46 ` Johannes Weiner
2022-04-20 14:25 ` Peter Xu
2022-04-05 1:49 ` [PATCH v8 23/23] selftests/uffd: Enable uffd-wp for shmem/hugetlbfs Peter Xu
2022-04-05 22:16 ` [PATCH v8 00/23] userfaultfd-wp: Support shmem and hugetlbfs Andrew Morton
2022-04-05 22:42 ` Peter Xu
2022-04-05 22:49 ` Andrew Morton
2022-04-05 23:02 ` Peter Xu
2022-04-05 23:08 ` Andrew Morton
2022-05-10 19:05 ` Andrew Morton
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