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mm/hugetlb: hook page faults for uffd write protection 

Hook up hugetlbfs_fault() with the capability to handle userfaultfd-wp
faults.

We do this slightly earlier than hugetlb_cow() so that we can avoid taking
some extra locks that we definitely don't need.

Link: https://lkml.kernel.org/r/20220405014901.14590-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Peter Xu 2022-05-12 20:22:54 -07:00 committed by Andrew Morton
parent 229f3fa778
commit 166f3ecc0d
1 changed files with 20 additions and 0 deletions
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20
mm/hugetlb.c
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@ -5737,6 +5737,26 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (unlikely(!pte_same(entry, huge_ptep_get(ptep))))
goto out_ptl;
/* Handle userfault-wp first, before trying to lock more pages */
if (userfaultfd_wp(vma) && huge_pte_uffd_wp(huge_ptep_get(ptep)) &&
(flags & FAULT_FLAG_WRITE) && !huge_pte_write(entry)) {
struct vm_fault vmf = {
.vma = vma,
.address = haddr,
.real_address = address,
.flags = flags,
};
spin_unlock(ptl);
if (pagecache_page) {
unlock_page(pagecache_page);
put_page(pagecache_page);
}
mutex_unlock(&hugetlb_fault_mutex_table[hash]);
i_mmap_unlock_read(mapping);
return handle_userfault(&vmf, VM_UFFD_WP);
}
/*
* hugetlb_wp() requires page locks of pte_page(entry) and
* pagecache_page, so here we need take the former one