From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>,
Jerome Glisse <jglisse@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Hugh Dickins <hughd@google.com>,
peterx@redhat.com, Nadav Amit <nadav.amit@gmail.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>
Subject: [PATCH 14/23] shmem/userfaultfd: Pass over uffd-wp special swap pte when fork()
Date: Mon, 22 Mar 2021 20:49:03 -0400 [thread overview]
Message-ID: <20210323004912.35132-15-peterx@redhat.com> (raw)
In-Reply-To: <20210323004912.35132-1-peterx@redhat.com>
It should be handled similarly like other uffd-wp wr-protected ptes: we should
pass it over when the dst_vma has VM_UFFD_WP armed, otherwise drop it.
Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/memory.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/mm/memory.c b/mm/memory.c
index 8be28bcaa044..766946d3eab0 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -715,8 +715,21 @@ copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
unsigned long vm_flags = dst_vma->vm_flags;
pte_t pte = *src_pte;
struct page *page;
- swp_entry_t entry = pte_to_swp_entry(pte);
+ swp_entry_t entry;
+
+ if (unlikely(is_swap_special_pte(pte))) {
+ /*
+ * uffd-wp special swap pte is the only possibility for now.
+ * If dst vma is registered with uffd-wp, copy it over.
+ * Otherwise, ignore this pte as if it's a none pte would work.
+ */
+ WARN_ON_ONCE(!pte_swp_uffd_wp_special(pte));
+ if (userfaultfd_wp(dst_vma))
+ set_pte_at(dst_mm, addr, dst_pte, pte);
+ return 0;
+ }
+ entry = pte_to_swp_entry(pte);
if (likely(!non_swap_entry(entry))) {
if (swap_duplicate(entry) < 0)
return entry.val;
--
2.26.2
next prev parent reply other threads:[~2021-03-23 0:49 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 0:48 [PATCH 00/23] userfaultfd-wp: Support shmem and hugetlbfs Peter Xu
2021-03-23 0:48 ` [PATCH 01/23] shmem/userfaultfd: Take care of UFFDIO_COPY_MODE_WP Peter Xu
2021-03-23 0:48 ` [PATCH 02/23] mm: Clear vmf->pte after pte_unmap_same() returns Peter Xu
2021-03-23 2:34 ` Miaohe Lin
2021-03-23 15:40 ` Peter Xu
2021-03-23 0:48 ` [PATCH 03/23] mm/userfaultfd: Introduce special pte for unmapped file-backed mem Peter Xu
2021-03-23 0:48 ` [PATCH 04/23] mm/swap: Introduce the idea of special swap ptes Peter Xu
2021-03-23 0:48 ` [PATCH 05/23] shmem/userfaultfd: Handle uffd-wp special pte in page fault handler Peter Xu
2021-03-23 0:48 ` [PATCH 06/23] mm: Drop first_index/last_index in zap_details Peter Xu
2021-03-23 0:48 ` [PATCH 07/23] mm: Introduce zap_details.zap_flags Peter Xu
2021-03-23 2:11 ` Matthew Wilcox
2021-03-23 15:43 ` Peter Xu
2021-03-23 0:48 ` [PATCH 08/23] mm: Introduce ZAP_FLAG_SKIP_SWAP Peter Xu
2021-03-23 0:48 ` [PATCH 09/23] mm: Pass zap_flags into unmap_mapping_pages() Peter Xu
2021-03-23 0:48 ` [PATCH 10/23] shmem/userfaultfd: Persist uffd-wp bit across zapping for file-backed Peter Xu
2021-03-23 0:49 ` [PATCH 11/23] shmem/userfaultfd: Allow wr-protect none pte for file-backed mem Peter Xu
2021-03-23 0:49 ` [PATCH 12/23] shmem/userfaultfd: Allows file-back mem to be uffd wr-protected on thps Peter Xu
2021-03-23 0:49 ` [PATCH 13/23] shmem/userfaultfd: Handle the left-overed special swap ptes Peter Xu
2021-03-23 0:49 ` Peter Xu [this message]
2021-03-23 0:49 ` [PATCH 15/23] hugetlb/userfaultfd: Hook page faults for uffd write protection Peter Xu
2021-04-21 22:02 ` Mike Kravetz
2021-03-23 0:49 ` [PATCH 16/23] hugetlb/userfaultfd: Take care of UFFDIO_COPY_MODE_WP Peter Xu
2021-04-21 23:06 ` Mike Kravetz
2021-04-22 1:14 ` Peter Xu
2021-03-23 0:49 ` [PATCH 17/23] hugetlb/userfaultfd: Handle UFFDIO_WRITEPROTECT Peter Xu
2021-04-22 18:22 ` Mike Kravetz
2021-03-23 0:49 ` [PATCH 18/23] mm/hugetlb: Introduce huge version of special swap pte helpers Peter Xu
2021-04-22 19:00 ` Mike Kravetz
2021-03-23 0:50 ` [PATCH 19/23] hugetlb/userfaultfd: Handle uffd-wp special pte in hugetlb pf handler Peter Xu
2021-04-22 22:45 ` Mike Kravetz
2021-04-26 2:08 ` Peter Xu
2021-03-23 0:50 ` [PATCH 20/23] hugetlb/userfaultfd: Allow wr-protect none ptes Peter Xu
2021-04-23 0:08 ` Mike Kravetz
2021-03-23 0:50 ` [PATCH 21/23] hugetlb/userfaultfd: Only drop uffd-wp special pte if required Peter Xu
2021-04-23 20:33 ` Mike Kravetz
2021-04-26 21:16 ` Peter Xu
2021-04-26 21:36 ` Mike Kravetz
2021-04-26 22:05 ` Peter Xu
2021-04-26 23:09 ` Mike Kravetz
2021-03-23 0:50 ` [PATCH 22/23] mm/userfaultfd: Enable write protection for shmem & hugetlbfs Peter Xu
2021-03-23 0:50 ` [PATCH 23/23] userfaultfd/selftests: Enable uffd-wp for shmem/hugetlbfs Peter Xu
2021-03-23 0:54 ` [PATCH 00/23] userfaultfd-wp: Support shmem and hugetlbfs Peter Xu
2021-04-21 16:03 ` Peter Xu
2021-04-21 21:39 ` Mike Kravetz
2021-04-22 1:16 ` Peter Xu
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