The patch titled
Subject: maple_tree: check for MA_STATE_BULK on setting wr_rebalance
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
maple_tree-check-for-ma_state_bulk-on-setting-wr_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-check-for-ma_state_bulk-on-setting-wr_rebalance.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
Subject: maple_tree: check for MA_STATE_BULK on setting wr_rebalance
Date: Fri, 11 Oct 2024 17:44:50 -0400
It is possible for a bulk operation (MA_STATE_BULK is set) to enter the
new_end < mt_min_slots[type] case and set wr_rebalance as a store type.
This is incorrect as bulk stores do not rebalance per write, but rather
after the all of the writes are done through the mas_bulk_rebalance()
path. Therefore, add a check to make sure MA_STATE_BULK is not set before
we return wr_rebalance as the store type.
Also add a test to make sure wr_rebalance is never the store type when
doing bulk operations via mas_expected_entries()
This is a hotfix for this rc however it has no userspace effects as there
are no users of the bulk insertion mode.
Link: https://lkml.kernel.org/r/20241011214451.7286-1-sidhartha.kumar@xxxxxxxxxx
Fixes: 5d659bbb52a2 ("maple_tree: introduce mas_wr_store_type()")
Suggested-by: Liam Howlett <liam.howlett@xxxxxxxxxx>
Signed-off-by: Sidhartha <sidhartha.kumar@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/maple_tree.c | 2 +-
tools/testing/radix-tree/maple.c | 26 ++++++++++++++++++++++++++
2 files changed, 27 insertions(+), 1 deletion(-)
--- a/lib/maple_tree.c~maple_tree-check-for-ma_state_bulk-on-setting-wr_rebalance
+++ a/lib/maple_tree.c
@@ -4218,7 +4218,7 @@ static inline void mas_wr_store_type(str
/* Potential spanning rebalance collapsing a node */
if (new_end < mt_min_slots[wr_mas->type]) {
- if (!mte_is_root(mas->node)) {
+ if (!mte_is_root(mas->node) && !(mas->mas_flags & MA_STATE_BULK)) {
mas->store_type = wr_rebalance;
return;
}
--- a/tools/testing/radix-tree/maple.c~maple_tree-check-for-ma_state_bulk-on-setting-wr_rebalance
+++ a/tools/testing/radix-tree/maple.c
@@ -36317,6 +36317,28 @@ static inline int check_vma_modification
return 0;
}
+/*
+ * test to check that bulk stores do not use wr_rebalance as the store
+ * type.
+ */
+static inline void check_bulk_rebalance(struct maple_tree *mt)
+{
+ MA_STATE(mas, mt, ULONG_MAX, ULONG_MAX);
+ int max = 10;
+
+ build_full_tree(mt, 0, 2);
+
+ /* erase every entry in the tree */
+ do {
+ /* set up bulk store mode */
+ mas_expected_entries(&mas, max);
+ mas_erase(&mas);
+ MT_BUG_ON(mt, mas.store_type == wr_rebalance);
+ } while (mas_prev(&mas, 0) != NULL);
+
+ mas_destroy(&mas);
+}
+
void farmer_tests(void)
{
struct maple_node *node;
@@ -36328,6 +36350,10 @@ void farmer_tests(void)
check_vma_modification(&tree);
mtree_destroy(&tree);
+ mt_init(&tree);
+ check_bulk_rebalance(&tree);
+ mtree_destroy(&tree);
+
tree.ma_root = xa_mk_value(0);
mt_dump(&tree, mt_dump_dec);
_
Patches currently in -mm which might be from sidhartha.kumar@xxxxxxxxxx are
maple_tree-check-for-ma_state_bulk-on-setting-wr_rebalance.patch
maple_tree-remove-conditionals-to-detect-wr_node_store.patch
