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 15/23] mm/hugetlb: Handle pte markers in page faults
Date: Mon, 4 Apr 2022 21:49:09 -0400 [thread overview]
Message-ID: <20220405014909.14761-1-peterx@redhat.com> (raw)
In-Reply-To: <20220405014646.13522-1-peterx@redhat.com>
Allow hugetlb code to handle pte markers just like none ptes. It's mostly
there, we just need to make sure we don't assume hugetlb_no_page() only handles
none pte, so when detecting pte change we should use pte_same() rather than
pte_none(). We need to pass in the old_pte to do the comparison.
Check the original pte to see whether it's a pte marker, if it is, we should
recover uffd-wp bit on the new pte to be installed, so that the next write will
be trapped by uffd.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/hugetlb.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2401dd5997b7..9317b790161d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5412,7 +5412,8 @@ static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma,
static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
struct vm_area_struct *vma,
struct address_space *mapping, pgoff_t idx,
- unsigned long address, pte_t *ptep, unsigned int flags)
+ unsigned long address, pte_t *ptep,
+ pte_t old_pte, unsigned int flags)
{
struct hstate *h = hstate_vma(vma);
vm_fault_t ret = VM_FAULT_SIGBUS;
@@ -5539,7 +5540,8 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
ptl = huge_pte_lock(h, mm, ptep);
ret = 0;
- if (!huge_pte_none(huge_ptep_get(ptep)))
+ /* If pte changed from under us, retry */
+ if (!pte_same(huge_ptep_get(ptep), old_pte))
goto backout;
if (anon_rmap) {
@@ -5549,6 +5551,12 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
page_dup_file_rmap(page, true);
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED)));
+ /*
+ * If this pte was previously wr-protected, keep it wr-protected even
+ * if populated.
+ */
+ if (unlikely(pte_marker_uffd_wp(old_pte)))
+ new_pte = huge_pte_wrprotect(huge_pte_mkuffd_wp(new_pte));
set_huge_pte_at(mm, haddr, ptep, new_pte);
hugetlb_count_add(pages_per_huge_page(h), mm);
@@ -5666,8 +5674,10 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
mutex_lock(&hugetlb_fault_mutex_table[hash]);
entry = huge_ptep_get(ptep);
- if (huge_pte_none(entry)) {
- ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep, flags);
+ /* PTE markers should be handled the same way as none pte */
+ if (huge_pte_none_mostly(entry)) {
+ ret = hugetlb_no_page(mm, vma, mapping, idx, address, ptep,
+ entry, flags);
goto out_mutex;
}
--
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 ` [PATCH v8 09/23] mm/shmem: Allows file-back mem to be uffd wr-protected on thps Peter Xu
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 ` Peter Xu [this message]
2022-04-06 13:37 ` [PATCH v8 15/23] mm/hugetlb: Handle pte markers in page faults 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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