From 8f62bd4c819b6534eda960f812222093e67479c1 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Wed, 13 Apr 2022 23:07:13 -0700 Subject: [PATCH] mm/mmap: use the maple tree for find_vma_prev() instead of the rbtree Use the maple tree's advanced API and a maple state to walk the tree for the entry at the address of the next vma, then use the maple state to walk back one entry to find the previous entry. Add kernel documentation comments for this API. Signed-off-by: Liam R. Howlett Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Vlastimil Babka --- mm/mmap.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index b8679fd1f7e3..dfb2b2ddee24 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2481,23 +2481,30 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) } EXPORT_SYMBOL(find_vma); -/* - * Same as find_vma, but also return a pointer to the previous VMA in *pprev. +/** + * find_vma_prev() - Find the VMA for a given address, or the next vma and + * set %pprev to the previous VMA, if any. + * @mm: The mm_struct to check + * @addr: The address + * @pprev: The pointer to set to the previous VMA + * + * Note that RCU lock is missing here since the external mmap_lock() is used + * instead. + * + * Returns: The VMA associated with @addr, or the next vma. + * May return %NULL in the case of no vma at addr or above. */ struct vm_area_struct * find_vma_prev(struct mm_struct *mm, unsigned long addr, struct vm_area_struct **pprev) { struct vm_area_struct *vma; + MA_STATE(mas, &mm->mm_mt, addr, addr); - vma = find_vma(mm, addr); - if (vma) { - *pprev = vma->vm_prev; - } else { - struct rb_node *rb_node = rb_last(&mm->mm_rb); - - *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL; - } + vma = mas_walk(&mas); + *pprev = mas_prev(&mas, 0); + if (!vma) + vma = mas_next(&mas, ULONG_MAX); return vma; } -- 2.50.1