+ mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust.patch added to mm-unstable branch

* + mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust.patch added to mm-unstable branch
@ 2023-01-21  1:07 Andrew Morton
  0 siblings, 0 replies; 2+ messages in thread
From: Andrew Morton @ 2023-01-21  1:07 UTC (permalink / raw)
  To: mm-commits, Liam.Howlett, Liam.Howlett, akpm


The patch titled
     Subject: mm: remove unnecessary write to vma iterator in __vma_adjust()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Subject: mm: remove unnecessary write to vma iterator in __vma_adjust()
Date: Fri, 20 Jan 2023 11:26:35 -0500

If the vma start address is going to change due to an insert, then it is
safe to not write the vma to the tree.  The write of the insert vma will
alter the tree as necessary.

Link: https://lkml.kernel.org/r/20230120162650.984577-35-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

--- a/mm/mmap.c~mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust
+++ a/mm/mmap.c
@@ -722,10 +722,12 @@ int __vma_adjust(struct vma_iterator *vm
 	}
 
 	if (start != vma->vm_start) {
-		if ((vma->vm_start < start) &&
-		    (!insert || (insert->vm_end != start))) {
-			vma_iter_clear(vmi, vma->vm_start, start);
-			VM_WARN_ON(insert && insert->vm_start > vma->vm_start);
+		if (vma->vm_start < start) {
+			if (!insert || (insert->vm_end != start)) {
+				vma_iter_clear(vmi, vma->vm_start, start);
+				vma_iter_set(vmi, start);
+				VM_WARN_ON(insert && insert->vm_start > vma->vm_start);
+			}
 		} else {
 			vma_changed = true;
 		}
_

Patches currently in -mm which might be from Liam.Howlett@Oracle.com are

maple_tree-add-mas_init-function.patch
maple_tree-fix-potential-rcu-issue.patch
maple_tree-reduce-user-error-potential.patch
test_maple_tree-test-modifications-while-iterating.patch
mm-expand-vma-iterator-interface.patch
mm-mmap-convert-brk-to-use-vma-iterator.patch
kernel-fork-convert-forking-to-using-the-vmi-iterator.patch
mmap-convert-vma_link-vma-iterator.patch
mm-mmap-remove-preallocation-from-do_mas_align_munmap.patch
mmap-change-do_mas_munmap-and-do_mas_aligned_munmap-to-use-vma-iterator.patch
mmap-convert-vma_expand-to-use-vma-iterator.patch
mm-add-temporary-vma-iterator-versions-of-vma_merge-split_vma-and-__split_vma.patch
ipc-shm-use-the-vma-iterator-for-munmap-calls.patch
userfaultfd-use-vma-iterator.patch
mm-change-mprotect_fixup-to-vma-iterator.patch
mlock-convert-mlock-to-vma-iterator.patch
coredump-convert-to-vma-iterator.patch
mempolicy-convert-to-vma-iterator.patch
task_mmu-convert-to-vma-iterator.patch
sched-convert-to-vma-iterator.patch
madvise-use-vmi-iterator-for-__split_vma-and-vma_merge.patch
mmap-pass-through-vmi-iterator-to-__split_vma.patch
mmap-use-vmi-version-of-vma_merge.patch
mm-mremap-use-vmi-version-of-vma_merge.patch
nommu-convert-nommu-to-using-the-vma-iterator.patch
mm-switch-vma_merge-split_vma-and-__split_vma-to-vma-iterator.patch
mmap-convert-__vma_adjust-to-use-vma-iterator.patch
mm-pass-through-vma-iterator-to-__vma_adjust.patch
madvise-use-split_vma-instead-of-__split_vma.patch
mm-remove-unnecessary-write-to-vma-iterator-in-__vma_adjust.patch
mm-pass-vma-iterator-through-to-__vma_adjust.patch
mm-add-vma-iterator-to-vma_adjust-arguments.patch
mmap-clean-up-mmap_region-unrolling.patch
mm-change-munmap-splitting-order-and-move_vma.patch
mm-mmap-move-anon_vma-setting-in-__vma_adjust.patch
mm-mmap-refactor-locking-out-of-__vma_adjust.patch
mm-mmap-use-vma_prepare-and-vma_complete-in-vma_expand.patch
mm-mmap-introduce-init_vma_prep-and-init_multi_vma_prep.patch
mm-dont-use-__vma_adjust-in-__split_vma.patch
mm-mmap-dont-use-__vma_adjust-in-shift_arg_pages.patch
mm-mmap-introduce-dup_vma_anon-helper.patch
mm-mmap-convert-do_brk_flags-to-use-vma_prepare-and-vma_complete.patch
mm-mmap-remove-__vma_adjust.patch
vma_merge-set-vma-iterator-to-correct-position.patch


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