+ maple_tree-adjust-node-allocation-on-mas_rebalance.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: maple_tree: adjust node allocation on mas_rebalance()
has been added to the -mm mm-unstable branch.  Its filename is
     maple_tree-adjust-node-allocation-on-mas_rebalance.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-adjust-node-allocation-on-mas_rebalance.patch

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Subject: maple_tree: adjust node allocation on mas_rebalance()
Date: Mon, 12 Jun 2023 16:39:45 -0400

mas_rebalance() is called to rebalance an insufficient node into a single
node or two sufficient nodes.  The preallocation estimate is always too
many in this case as the height of the tree will never grow and there is
no possibility to have a three way split in this case, so revise the node
allocation count.

Link: https://lkml.kernel.org/r/20230612203953.2093911-9-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/maple_tree.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/lib/maple_tree.c~maple_tree-adjust-node-allocation-on-mas_rebalance
+++ a/lib/maple_tree.c
@@ -3166,7 +3166,7 @@ static inline int mas_rebalance(struct m
 	 * tries to combine the data in the same way.  If one node contains the
 	 * entire range of the tree, then that node is used as a new root node.
 	 */
-	mas_node_count(mas, 1 + empty_count * 3);
+	mas_node_count(mas, empty_count * 2 - 1);
 	if (mas_is_err(mas))
 		return 0;
 
_

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

mm-mprotect-fix-do_mprotect_pkey-limit-check.patch
maple_tree-add-benchmarking-for-mas_for_each.patch
maple_tree-add-benchmarking-for-mas_prev.patch
mm-move-unmap_vmas-declaration-to-internal-header.patch
mm-change-do_vmi_align_munmap-side-tree-index.patch
mm-remove-prev-check-from-do_vmi_align_munmap.patch
maple_tree-introduce-__mas_set_range.patch
mm-remove-re-walk-from-mmap_region.patch
maple_tree-adjust-node-allocation-on-mas_rebalance.patch
maple_tree-re-introduce-entry-to-mas_preallocate-arguments.patch
mm-use-vma_iter_clear_gfp-in-nommu.patch
mm-set-up-vma-iterator-for-vma_iter_prealloc-calls.patch
maple_tree-move-mas_wr_end_piv-below-mas_wr_extend_null.patch
maple_tree-update-mas_preallocate-testing.patch
maple_tree-refine-mas_preallocate-node-calculations.patch
maple_tree-reduce-resets-during-store-setup.patch
mm-mmap-change-vma-iteration-order-in-do_vmi_align_munmap.patch
userfaultfd-fix-regression-in-userfaultfd_unmap_prep.patch