diff options
| -rw-r--r-- | mm/mmap.c | 3 | ||||
| -rw-r--r-- | mm/vma.c | 23 | ||||
| -rw-r--r-- | mm/vma.h | 14 |
3 files changed, 31 insertions, 9 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 3f1419460be3..582036922d05 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1756,7 +1756,8 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, VMG_STATE(vmg, mm, vmi, addr, addr + len, flags, PHYS_PFN(addr)); vmg.prev = vma; - vma_iter_next_range(vmi); + /* vmi is positioned at prev, which this mode expects. */ + vmg.merge_flags = VMG_FLAG_JUST_EXPAND; if (vma_merge_new_range(&vmg)) goto out; @@ -917,6 +917,7 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) pgoff_t pgoff = vmg->pgoff; pgoff_t pglen = PHYS_PFN(end - start); bool can_merge_left, can_merge_right; + bool just_expand = vmg->merge_flags & VMG_FLAG_JUST_EXPAND; mmap_assert_write_locked(vmg->mm); VM_WARN_ON(vmg->vma); @@ -930,7 +931,7 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) return NULL; can_merge_left = can_vma_merge_left(vmg); - can_merge_right = can_vma_merge_right(vmg, can_merge_left); + can_merge_right = !just_expand && can_vma_merge_right(vmg, can_merge_left); /* If we can merge with the next VMA, adjust vmg accordingly. */ if (can_merge_right) { @@ -953,7 +954,11 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) if (can_merge_right && !can_merge_remove_vma(next)) vmg->end = end; - vma_prev(vmg->vmi); /* Equivalent to going to the previous range */ + /* In expand-only case we are already positioned at prev. */ + if (!just_expand) { + /* Equivalent to going to the previous range. */ + vma_prev(vmg->vmi); + } } /* @@ -967,12 +972,14 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) } /* If expansion failed, reset state. Allows us to retry merge later. */ - vmg->vma = NULL; - vmg->start = start; - vmg->end = end; - vmg->pgoff = pgoff; - if (vmg->vma == prev) - vma_iter_set(vmg->vmi, start); + if (!just_expand) { + vmg->vma = NULL; + vmg->start = start; + vmg->end = end; + vmg->pgoff = pgoff; + if (vmg->vma == prev) + vma_iter_set(vmg->vmi, start); + } return NULL; } @@ -59,6 +59,17 @@ enum vma_merge_state { VMA_MERGE_SUCCESS, }; +enum vma_merge_flags { + VMG_FLAG_DEFAULT = 0, + /* + * If we can expand, simply do so. We know there is nothing to merge to + * the right. Does not reset state upon failure to merge. The VMA + * iterator is assumed to be positioned at the previous VMA, rather than + * at the gap. + */ + VMG_FLAG_JUST_EXPAND = 1 << 0, +}; + /* Represents a VMA merge operation. */ struct vma_merge_struct { struct mm_struct *mm; @@ -75,6 +86,7 @@ struct vma_merge_struct { struct mempolicy *policy; struct vm_userfaultfd_ctx uffd_ctx; struct anon_vma_name *anon_name; + enum vma_merge_flags merge_flags; enum vma_merge_state state; }; @@ -99,6 +111,7 @@ static inline pgoff_t vma_pgoff_offset(struct vm_area_struct *vma, .flags = flags_, \ .pgoff = pgoff_, \ .state = VMA_MERGE_START, \ + .merge_flags = VMG_FLAG_DEFAULT, \ } #define VMG_VMA_STATE(name, vmi_, prev_, vma_, start_, end_) \ @@ -118,6 +131,7 @@ static inline pgoff_t vma_pgoff_offset(struct vm_area_struct *vma, .uffd_ctx = vma_->vm_userfaultfd_ctx, \ .anon_name = anon_vma_name(vma_), \ .state = VMA_MERGE_START, \ + .merge_flags = VMG_FLAG_DEFAULT, \ } #ifdef CONFIG_DEBUG_VM_MAPLE_TREE |