diff options
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 38 |
1 files changed, 6 insertions, 32 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index f904b3bba962..386429f7db5a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1039,6 +1039,8 @@ static int expand_upwards(struct vm_area_struct *vma, unsigned long address) if (!(vma->vm_flags & VM_GROWSUP)) return -EFAULT; + mmap_assert_write_locked(mm); + /* Guard against exceeding limits of the address space. */ address &= PAGE_MASK; if (address >= (TASK_SIZE & PAGE_MASK)) @@ -1074,11 +1076,7 @@ static int expand_upwards(struct vm_area_struct *vma, unsigned long address) /* Lock the VMA before expanding to prevent concurrent page faults */ vma_start_write(vma); - /* - * vma->vm_start/vm_end cannot change under us because the caller - * is required to hold the mmap_lock in read mode. We need the - * anon_vma lock to serialize against concurrent expand_stacks. - */ + /* We update the anon VMA tree. */ anon_vma_lock_write(vma->anon_vma); /* Somebody else might have raced and expanded it already */ @@ -1092,16 +1090,6 @@ static 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) { - /* - * We only hold a shared mmap_lock lock here, so - * we need to protect against concurrent vma - * expansions. anon_vma_lock_write() 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(&mm->page_table_lock); if (vma->vm_flags & VM_LOCKED) mm->locked_vm += grow; vm_stat_account(mm, vma->vm_flags, grow); @@ -1110,7 +1098,6 @@ static int expand_upwards(struct vm_area_struct *vma, unsigned long address) /* Overwrite old entry in mtree. */ vma_iter_store(&vmi, vma); anon_vma_interval_tree_post_update_vma(vma); - spin_unlock(&mm->page_table_lock); perf_event_mmap(vma); } @@ -1137,6 +1124,8 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) if (!(vma->vm_flags & VM_GROWSDOWN)) return -EFAULT; + mmap_assert_write_locked(mm); + address &= PAGE_MASK; if (address < mmap_min_addr || address < FIRST_USER_ADDRESS) return -EPERM; @@ -1166,11 +1155,7 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) /* Lock the VMA before expanding to prevent concurrent page faults */ vma_start_write(vma); - /* - * vma->vm_start/vm_end cannot change under us because the caller - * is required to hold the mmap_lock in read mode. We need the - * anon_vma lock to serialize against concurrent expand_stacks. - */ + /* We update the anon VMA tree. */ anon_vma_lock_write(vma->anon_vma); /* Somebody else might have raced and expanded it already */ @@ -1184,16 +1169,6 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) if (grow <= vma->vm_pgoff) { error = acct_stack_growth(vma, size, grow); if (!error) { - /* - * We only hold a shared mmap_lock lock here, so - * we need to protect against concurrent vma - * expansions. anon_vma_lock_write() 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(&mm->page_table_lock); if (vma->vm_flags & VM_LOCKED) mm->locked_vm += grow; vm_stat_account(mm, vma->vm_flags, grow); @@ -1203,7 +1178,6 @@ int expand_downwards(struct vm_area_struct *vma, unsigned long address) /* Overwrite old entry in mtree. */ vma_iter_store(&vmi, vma); anon_vma_interval_tree_post_update_vma(vma); - spin_unlock(&mm->page_table_lock); perf_event_mmap(vma); } |