diff options
| author | Suren Baghdasaryan <surenb@google.com> | 2023-08-04 08:27:22 -0700 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-21 13:37:46 -0700 |
| commit | 60081bf19b0ec8fa40c589bd361fa2bc763f1050 (patch) | |
| tree | b4c4909b23e49edc487efcd44d983fb2f2af6334 /mm/madvise.c | |
| parent | e727bfd5e73a35ecbc4a01a15c659b9fafaa97c0 (diff) | |
| download | lwn-60081bf19b0ec8fa40c589bd361fa2bc763f1050.tar.gz lwn-60081bf19b0ec8fa40c589bd361fa2bc763f1050.zip | |
mm: lock vma explicitly before doing vm_flags_reset and vm_flags_reset_once
Implicit vma locking inside vm_flags_reset() and vm_flags_reset_once() is
not obvious and makes it hard to understand where vma locking is happening.
Also in some cases (like in dup_userfaultfd()) vma should be locked earlier
than vma_flags modification. To make locking more visible, change these
functions to assert that the vma write lock is taken and explicitly lock
the vma beforehand. Fix userfaultfd functions which should lock the vma
earlier.
Link: https://lkml.kernel.org/r/20230804152724.3090321-5-surenb@google.com
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/madvise.c')
| -rw-r--r-- | mm/madvise.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/mm/madvise.c b/mm/madvise.c index da65f8bd9ac3..8498f700c284 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -173,9 +173,8 @@ static int madvise_update_vma(struct vm_area_struct *vma, } success: - /* - * vm_flags is protected by the mmap_lock held in write mode. - */ + /* vm_flags is protected by the mmap_lock held in write mode. */ + vma_start_write(vma); vm_flags_reset(vma, new_flags); if (!vma->vm_file || vma_is_anon_shmem(vma)) { error = replace_anon_vma_name(vma, anon_name); |