The patch titled
Subject: lib/interval_tree: skip the check before go to the right subtree
has been added to the -mm mm-nonmm-unstable branch. Its filename is
lib-interval_tree-skip-the-check-before-go-to-the-right-subtree.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-interval_tree-skip-the-check-before-go-to-the-right-subtree.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Wei Yang <richard.weiyang@xxxxxxxxx>
Subject: lib/interval_tree: skip the check before go to the right subtree
Date: Mon, 24 Feb 2025 02:22:39 +0000
The interval_tree_subtree_search() holds the loop invariant:
start <= node->ITSUBTREE
Let's say we have a following tree:
node
/ \
left right
So we know node->ITSUBTREE is contributed by one of the following:
* left->ITSUBTREE
* ITLAST(node)
* right->ITSUBTREE
When we come to the right node, we are sure the first two don't
contribute to node->ITSUBTREE and it must be the right node does the
job.
So skip the check before go to the right subtree.
Link: https://lkml.kernel.org/r/20250224022239.21976-1-richard.weiyang@xxxxxxxxx
Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michel Lespinasse <michel@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/interval_tree_generic.h | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
--- a/include/linux/interval_tree_generic.h~lib-interval_tree-skip-the-check-before-go-to-the-right-subtree
+++ a/include/linux/interval_tree_generic.h
@@ -104,12 +104,8 @@ ITPREFIX ## _subtree_search(ITSTRUCT *no
if (ITSTART(node) <= last) { /* Cond1 */ \
if (start <= ITLAST(node)) /* Cond2 */ \
return node; /* node is leftmost match */ \
- if (node->ITRB.rb_right) { \
- node = rb_entry(node->ITRB.rb_right, \
- ITSTRUCT, ITRB); \
- if (start <= node->ITSUBTREE) \
- continue; \
- } \
+ node = rb_entry(node->ITRB.rb_right, ITSTRUCT, ITRB); \
+ continue; \
} \
return NULL; /* No match */ \
} \
_
Patches currently in -mm which might be from richard.weiyang@xxxxxxxxx are
mm-mm_initc-use-round_up-to-align-movable-range.patch
mm-mm_initc-only-align-start-of-zone_movalbe-on-nodes-with-memory.patch
mm-mm_initc-use-round_up-to-calculate-usermap-size.patch
lib-interval_tree-skip-the-check-before-go-to-the-right-subtree.patch
