From 54492a9e7c411d0f3f5e73f8f1d190908cdd3abe Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Sun, 5 Sep 2021 23:31:15 -0400 Subject: [PATCH] mmap: Change zeroing of maple tree in __vma_adjust Only write to the maple tree if we are not inserting or the insert isn't going to overwrite the area to clear. This avoids spanning writes and node coealescing when unnecessary. Signed-off-by: Liam R. Howlett --- mm/mmap.c | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 93ed19b2c6ce..c5f92666d145 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -615,6 +615,7 @@ int __vma_adjust(struct vm_area_struct *vma, unsigned long start, bool vma_changed = false; long adjust_next = 0; int remove_next = 0; + unsigned long old_start; if (next && !insert) { struct vm_area_struct *exporter = NULL, *importer = NULL; @@ -740,25 +741,29 @@ again: vma_interval_tree_remove(next, root); } + old_start = vma->vm_start; if (start != vma->vm_start) { - if (vma->vm_start < start) - vma_mt_szero(mm, vma->vm_start, start); - else - vma_changed = true; + vma_changed = true; vma->vm_start = start; } if (end != vma->vm_end) { - if (vma->vm_end > end) - vma_mt_szero(mm, end, vma->vm_end); - else + if (vma->vm_end > end) { + if (!insert || (insert && (insert->vm_start != end))) + vma_mt_szero(mm, end, vma->vm_end); + } else vma_changed = true; vma->vm_end = end; if (!next) mm->highest_vm_end = vm_end_gap(vma); } - if (vma_changed) + if (vma_changed) { vma_store(mm, vma); + if (old_start < start) { + if (insert && (insert->vm_start != old_start)) + vma_mt_szero(mm, old_start, start); + } + } vma->vm_pgoff = pgoff; if (adjust_next) { -- 2.50.1