diff options
| author | Suren Baghdasaryan <surenb@google.com> | 2023-02-27 09:36:20 -0800 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-04-05 20:02:59 -0700 |
| commit | eeff9a5d47f89bc641034fea05501c8a6de131cb (patch) | |
| tree | 851af9a8b1788fb18c749a0652c8ce11a67600a1 /mm/mmap.c | |
| parent | f2e13784c16a98e269b3111ac02ae44446dd589c (diff) | |
| download | lwn-eeff9a5d47f89bc641034fea05501c8a6de131cb.tar.gz lwn-eeff9a5d47f89bc641034fea05501c8a6de131cb.zip | |
mm/mmap: prevent pagefault handler from racing with mmu_notifier registration
Page fault handlers might need to fire MMU notifications while a new
notifier is being registered. Modify mm_take_all_locks to write-lock all
VMAs and prevent this race with page fault handlers that would hold VMA
locks. VMAs are locked before i_mmap_rwsem and anon_vma to keep the same
locking order as in page fault handlers.
Link: https://lkml.kernel.org/r/20230227173632.3292573-22-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 58704ca5acd2..18aed0ea6bd3 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3494,6 +3494,7 @@ static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) * of mm/rmap.c: * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for * hugetlb mapping); + * - all vmas marked locked * - all i_mmap_rwsem locks; * - all anon_vma->rwseml * @@ -3519,6 +3520,13 @@ int mm_take_all_locks(struct mm_struct *mm) mas_for_each(&mas, vma, ULONG_MAX) { if (signal_pending(current)) goto out_unlock; + vma_start_write(vma); + } + + mas_set(&mas, 0); + mas_for_each(&mas, vma, ULONG_MAX) { + if (signal_pending(current)) + goto out_unlock; if (vma->vm_file && vma->vm_file->f_mapping && is_vm_hugetlb_page(vma)) vm_lock_mapping(mm, vma->vm_file->f_mapping); @@ -3605,6 +3613,7 @@ void mm_drop_all_locks(struct mm_struct *mm) if (vma->vm_file && vma->vm_file->f_mapping) vm_unlock_mapping(vma->vm_file->f_mapping); } + vma_end_write_all(mm); mutex_unlock(&mm_all_locks_mutex); } |