The patch titled
Subject: maple_tree: fix mas_prev() state separation code
has been added to the -mm mm-unstable branch. Its filename is
maple_tree-separate-ma_state-node-from-status-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-separate-ma_state-node-from-status-fix.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@xxxxxxxxxx>
Subject: maple_tree: fix mas_prev() state separation code
Date: Thu, 7 Dec 2023 14:33:19 -0500
mas_prev() was setting the ma_underflow condition when the limit was
reached and not when the limit was attempting to go lower. This resulted
in the incorrect behaviour on subsequent actions.
This commit fixes the status setting to only set ma_underflow when the
lower limit is attempted to be decremented, and modifies the testing to
ensure that's the case.
Link: https://lkml.kernel.org/r/20231207193319.4025462-1-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/maple_tree.c | 16 ++++++++++++----
lib/test_maple_tree.c | 9 +++++++--
2 files changed, 19 insertions(+), 6 deletions(-)
--- a/lib/maple_tree.c~maple_tree-separate-ma_state-node-from-status-fix
+++ a/lib/maple_tree.c
@@ -4498,6 +4498,9 @@ again:
mas->last = mas->index - 1;
mas->index = mas_safe_min(mas, pivots, mas->offset);
} else {
+ if (mas->index <= min)
+ goto underflow;
+
if (mas_prev_node(mas, min)) {
mas_rewalk(mas, save_point);
goto retry;
@@ -4518,15 +4521,15 @@ again:
if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
goto retry;
- if (mas->index <= min)
- mas->status = ma_underflow;
if (likely(entry))
return entry;
if (!empty) {
- if (mas_is_underflow(mas))
+ if (mas->index <= min) {
+ mas->status = ma_underflow;
return NULL;
+ }
goto again;
}
@@ -4662,7 +4665,7 @@ retry:
if (unlikely(mas_rewalk_if_dead(mas, node, save_point)))
goto retry;
- if (pivot >= max) {
+ if (pivot >= max) { /* Was at the limit, next will extend beyond */
mas->status = ma_overflow;
return NULL;
}
@@ -4677,6 +4680,11 @@ again:
else
mas->last = mas->max;
} else {
+ if (mas->last >= max) {
+ mas->status = ma_overflow;
+ return NULL;
+ }
+
if (mas_next_node(mas, node, max)) {
mas_rewalk(mas, save_point);
goto retry;
--- a/lib/test_maple_tree.c~maple_tree-separate-ma_state-node-from-status-fix
+++ a/lib/test_maple_tree.c
@@ -3280,8 +3280,8 @@ static noinline void __init check_state_
MT_BUG_ON(mt, mas.last != 0x1500);
MT_BUG_ON(mt, !mas_is_active(&mas));
- /* next:active ->active */
- entry = mas_next(&mas, ULONG_MAX);
+ /* next:active ->active (spanning limit) */
+ entry = mas_next(&mas, 0x2100);
MT_BUG_ON(mt, entry != ptr2);
MT_BUG_ON(mt, mas.index != 0x2000);
MT_BUG_ON(mt, mas.last != 0x2500);
@@ -3346,6 +3346,11 @@ static noinline void __init check_state_
MT_BUG_ON(mt, entry != ptr);
MT_BUG_ON(mt, mas.index != 0x1000);
MT_BUG_ON(mt, mas.last != 0x1500);
+ MT_BUG_ON(mt, !mas_is_active(&mas)); /* spanning limit */
+ entry = mas_prev(&mas, 0x1200); /* underflow */
+ MT_BUG_ON(mt, entry != NULL);
+ MT_BUG_ON(mt, mas.index != 0x1000);
+ MT_BUG_ON(mt, mas.last != 0x1500);
MT_BUG_ON(mt, !mas_is_underflow(&mas));
/* prev:underflow -> underflow (lower limit) spanning end range */
_
Patches currently in -mm which might be from Liam.Howlett@xxxxxxxxxx are
maple_tree-remove-unnecessary-default-labels-from-switch-statements.patch
maple_tree-make-mas_erase-more-robust.patch
maple_tree-move-debug-check-to-__mas_set_range.patch
maple_tree-add-end-of-node-tracking-to-the-maple-state.patch
maple_tree-use-cached-node-end-in-mas_next.patch
maple_tree-use-cached-node-end-in-mas_destroy.patch
maple_tree-clean-up-inlines-for-some-functions.patch
maple_tree-separate-ma_state-node-from-status.patch
maple_tree-separate-ma_state-node-from-status-fix-1.patch
maple_tree-separate-ma_state-node-from-status-fix-2.patch
maple_tree-separate-ma_state-node-from-status-fix.patch
maple_tree-remove-mas_searchable.patch
maple_tree-use-maple-state-end-for-write-operations.patch
maple_tree-dont-find-node-end-in-mtree_lookup_walk.patch
maple_tree-mtree_range_walk-clean-up.patch
