From 9303d3e1c3f8d8863d561a070489cf44ce5e4103 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Fri, 20 Jan 2023 11:26:42 -0500 Subject: mm/mmap: use vma_prepare() and vma_complete() in vma_expand() Use the new locking functions for vma_expand(). This reduces code duplication. At the same time change VM_BUG_ON() to VM_WARN_ON() Link: https://lkml.kernel.org/r/20230120162650.984577-42-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Signed-off-by: Andrew Morton --- mm/mmap.c | 188 ++++++++++++++++++++++++-------------------------------------- 1 file changed, 72 insertions(+), 116 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 1ef284b7e6fb..b5bf70db3777 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -457,122 +457,6 @@ static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma) return 0; } -/* - * vma_expand - Expand an existing VMA - * - * @mas: The maple state - * @vma: The vma to expand - * @start: The start of the vma - * @end: The exclusive end of the vma - * @pgoff: The page offset of vma - * @next: The current of next vma. - * - * Expand @vma to @start and @end. Can expand off the start and end. Will - * expand over @next if it's different from @vma and @end == @next->vm_end. - * Checking if the @vma can expand and merge with @next needs to be handled by - * the caller. - * - * Returns: 0 on success - */ -inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, - unsigned long start, unsigned long end, pgoff_t pgoff, - struct vm_area_struct *next) -{ - struct mm_struct *mm = vma->vm_mm; - struct address_space *mapping = NULL; - struct rb_root_cached *root = NULL; - struct anon_vma *anon_vma = vma->anon_vma; - struct file *file = vma->vm_file; - bool remove_next = false; - - if (next && (vma != next) && (end == next->vm_end)) { - remove_next = true; - if (next->anon_vma && !vma->anon_vma) { - int error; - - anon_vma = next->anon_vma; - vma->anon_vma = anon_vma; - error = anon_vma_clone(vma, next); - if (error) - return error; - } - } - - /* Not merging but overwriting any part of next is not handled. */ - VM_BUG_ON(next && !remove_next && next != vma && end > next->vm_start); - /* Only handles expanding */ - VM_BUG_ON(vma->vm_start < start || vma->vm_end > end); - - if (vma_iter_prealloc(vmi)) - goto nomem; - - vma_adjust_trans_huge(vma, start, end, 0); - - if (file) { - mapping = file->f_mapping; - root = &mapping->i_mmap; - uprobe_munmap(vma, vma->vm_start, vma->vm_end); - i_mmap_lock_write(mapping); - } - - if (anon_vma) { - anon_vma_lock_write(anon_vma); - anon_vma_interval_tree_pre_update_vma(vma); - } - - if (file) { - flush_dcache_mmap_lock(mapping); - vma_interval_tree_remove(vma, root); - } - - /* VMA iterator points to previous, so set to start if necessary */ - if (vma_iter_addr(vmi) != start) - vma_iter_set(vmi, start); - - vma->vm_start = start; - vma->vm_end = end; - vma->vm_pgoff = pgoff; - vma_iter_store(vmi, vma); - - if (file) { - vma_interval_tree_insert(vma, root); - flush_dcache_mmap_unlock(mapping); - } - - /* Expanding over the next vma */ - if (remove_next && file) { - __remove_shared_vm_struct(next, file, mapping); - } - - if (anon_vma) { - anon_vma_interval_tree_post_update_vma(vma); - anon_vma_unlock_write(anon_vma); - } - - if (file) { - i_mmap_unlock_write(mapping); - uprobe_mmap(vma); - } - - if (remove_next) { - if (file) { - uprobe_munmap(next, next->vm_start, next->vm_end); - fput(file); - } - if (next->anon_vma) - anon_vma_merge(vma, next); - mm->map_count--; - mpol_put(vma_policy(next)); - vm_area_free(next); - } - - validate_mm(mm); - return 0; - -nomem: - return -ENOMEM; -} - /* * vma_prepare() - Helper function for handling locking VMAs prior to altering * @vp: The initialized vma_prepare struct @@ -694,6 +578,78 @@ again: uprobe_mmap(vp->insert); } +/* + * vma_expand - Expand an existing VMA + * + * @vmi: The vma iterator + * @vma: The vma to expand + * @start: The start of the vma + * @end: The exclusive end of the vma + * @pgoff: The page offset of vma + * @next: The current of next vma. + * + * Expand @vma to @start and @end. Can expand off the start and end. Will + * expand over @next if it's different from @vma and @end == @next->vm_end. + * Checking if the @vma can expand and merge with @next needs to be handled by + * the caller. + * + * Returns: 0 on success + */ +inline int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, + unsigned long start, unsigned long end, pgoff_t pgoff, + struct vm_area_struct *next) +{ + struct vma_prepare vp; + + memset(&vp, 0, sizeof(vp)); + vp.vma = vma; + vp.anon_vma = vma->anon_vma; + if (next && (vma != next) && (end == next->vm_end)) { + vp.remove = next; + if (next->anon_vma && !vma->anon_vma) { + int error; + + vp.anon_vma = next->anon_vma; + vma->anon_vma = next->anon_vma; + error = anon_vma_clone(vma, next); + if (error) + return error; + } + } + + /* Not merging but overwriting any part of next is not handled. */ + VM_WARN_ON(next && !vp.remove && + next != vma && end > next->vm_start); + /* Only handles expanding */ + VM_WARN_ON(vma->vm_start < start || vma->vm_end > end); + + if (vma_iter_prealloc(vmi)) + goto nomem; + + vma_adjust_trans_huge(vma, start, end, 0); + + vp.file = vma->vm_file; + if (vp.file) + vp.mapping = vp.file->f_mapping; + + /* VMA iterator points to previous, so set to start if necessary */ + if (vma_iter_addr(vmi) != start) + vma_iter_set(vmi, start); + + vma_prepare(&vp); + vma->vm_start = start; + vma->vm_end = end; + vma->vm_pgoff = pgoff; + /* Note: mas must be pointing to the expanding VMA */ + vma_iter_store(vmi, vma); + + vma_complete(&vp, vmi, vma->vm_mm); + validate_mm(vma->vm_mm); + return 0; + +nomem: + return -ENOMEM; +} /* * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that * is already present in an i_mmap tree without adjusting the tree. -- cgit v1.2.3