diff options
Diffstat (limited to 'mm/userfaultfd.c')
| -rw-r--r-- | mm/userfaultfd.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 0fdbd2c05587..e24e8a47ce8a 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -379,16 +379,21 @@ retry: BUG_ON(dst_addr >= dst_start + len); /* - * Serialize via hugetlb_fault_mutex. + * Serialize via vma_lock and hugetlb_fault_mutex. + * vma_lock ensures the dst_pte remains valid even + * in the case of shared pmds. fault mutex prevents + * races with other faulting threads. */ idx = linear_page_index(dst_vma, dst_addr); mapping = dst_vma->vm_file->f_mapping; hash = hugetlb_fault_mutex_hash(mapping, idx); mutex_lock(&hugetlb_fault_mutex_table[hash]); + hugetlb_vma_lock_read(dst_vma); err = -ENOMEM; dst_pte = huge_pte_alloc(dst_mm, dst_vma, dst_addr, vma_hpagesize); if (!dst_pte) { + hugetlb_vma_unlock_read(dst_vma); mutex_unlock(&hugetlb_fault_mutex_table[hash]); goto out_unlock; } @@ -396,6 +401,7 @@ retry: if (mode != MCOPY_ATOMIC_CONTINUE && !huge_pte_none_mostly(huge_ptep_get(dst_pte))) { err = -EEXIST; + hugetlb_vma_unlock_read(dst_vma); mutex_unlock(&hugetlb_fault_mutex_table[hash]); goto out_unlock; } @@ -404,6 +410,7 @@ retry: dst_addr, src_addr, mode, &page, wp_copy); + hugetlb_vma_unlock_read(dst_vma); mutex_unlock(&hugetlb_fault_mutex_table[hash]); cond_resched(); |