From 72346ccfed334160a40dbc7d106019c741d4a0b4 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 cee254c7e319..ff909eb0b9fb 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -638,6 +638,7 @@ 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; @@ -763,25 +764,29 @@ 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_mt_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