diff options
| -rw-r--r-- | mm/mmap.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 9ed3a06242a0..2b7d9e78a569 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2069,6 +2069,18 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { error = acct_stack_growth(vma, size, grow); if (!error) { + /* + * vma_gap_update() doesn't support concurrent + * updates, but we only hold a shared mmap_sem + * lock here, so we need to protect against + * concurrent vma expansions. + * vma_lock_anon_vma() doesn't help here, as + * we don't guarantee that all growable vmas + * in a mm share the same root anon vma. + * So, we reuse mm->page_table_lock to guard + * against concurrent vma expansions. + */ + spin_lock(&vma->vm_mm->page_table_lock); anon_vma_interval_tree_pre_update_vma(vma); vma->vm_end = address; anon_vma_interval_tree_post_update_vma(vma); @@ -2076,6 +2088,8 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) vma_gap_update(vma->vm_next); else vma->vm_mm->highest_vm_end = address; + spin_unlock(&vma->vm_mm->page_table_lock); + perf_event_mmap(vma); } } @@ -2126,11 +2140,25 @@ int expand_downwards(struct vm_area_struct *vma, if (grow <= vma->vm_pgoff) { error = acct_stack_growth(vma, size, grow); if (!error) { + /* + * vma_gap_update() doesn't support concurrent + * updates, but we only hold a shared mmap_sem + * lock here, so we need to protect against + * concurrent vma expansions. + * vma_lock_anon_vma() doesn't help here, as + * we don't guarantee that all growable vmas + * in a mm share the same root anon vma. + * So, we reuse mm->page_table_lock to guard + * against concurrent vma expansions. + */ + spin_lock(&vma->vm_mm->page_table_lock); anon_vma_interval_tree_pre_update_vma(vma); vma->vm_start = address; vma->vm_pgoff -= grow; anon_vma_interval_tree_post_update_vma(vma); vma_gap_update(vma); + spin_unlock(&vma->vm_mm->page_table_lock); + perf_event_mmap(vma); } } |