The patch titled
Subject: maple_tree: add mas_wr_new_end() to calculate new_end accurately
has been added to the -mm mm-unstable branch. Its filename is
maple_tree-add-mas_wr_new_end-to-calculate-new_end-accurately.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/maple_tree-add-mas_wr_new_end-to-calculate-new_end-accurately.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: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
Subject: maple_tree: add mas_wr_new_end() to calculate new_end accurately
Date: Wed, 24 May 2023 11:12:43 +0800
The previous new_end calculation is inaccurate, because it assumes that
two new pivots must be added (this is inaccurate), and sometimes it will
miss the fast path and enter the slow path. Add mas_wr_new_end() to
accurately calculate new_end to make the conditions for entering the fast
path more accurate.
Link: https://lkml.kernel.org/r/20230524031247.65949-7-zhangpeng.00@xxxxxxxxxxxxx
Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
Reviewed-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/maple_tree.c | 34 +++++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 11 deletions(-)
--- a/lib/maple_tree.c~maple_tree-add-mas_wr_new_end-to-calculate-new_end-accurately
+++ a/lib/maple_tree.c
@@ -4296,6 +4296,21 @@ static inline void mas_wr_extend_null(st
}
}
+static inline unsigned char mas_wr_new_end(struct ma_wr_state *wr_mas)
+{
+ struct ma_state *mas = wr_mas->mas;
+ unsigned char new_end = wr_mas->node_end + 2;
+
+ new_end -= wr_mas->offset_end - mas->offset;
+ if (wr_mas->r_min == mas->index)
+ new_end--;
+
+ if (wr_mas->end_piv == mas->last)
+ new_end--;
+
+ return new_end;
+}
+
static inline bool mas_wr_append(struct ma_wr_state *wr_mas)
{
unsigned char end = wr_mas->node_end;
@@ -4351,9 +4366,8 @@ static void mas_wr_bnode(struct ma_wr_st
static inline void mas_wr_modify(struct ma_wr_state *wr_mas)
{
- unsigned char node_slots;
- unsigned char node_size;
struct ma_state *mas = wr_mas->mas;
+ unsigned char new_end;
/* Direct replacement */
if (wr_mas->r_min == mas->index && wr_mas->r_max == mas->last) {
@@ -4363,17 +4377,15 @@ static inline void mas_wr_modify(struct
return;
}
- /* Attempt to append */
- node_slots = mt_slots[wr_mas->type];
- node_size = wr_mas->node_end - wr_mas->offset_end + mas->offset + 2;
- if (mas->max == ULONG_MAX)
- node_size++;
-
- /* slot and node store will not fit, go to the slow path */
- if (unlikely(node_size >= node_slots))
+ /*
+ * new_end exceeds the size of the maple node and cannot enter the fast
+ * path.
+ */
+ new_end = mas_wr_new_end(wr_mas);
+ if (new_end >= mt_slots[wr_mas->type])
goto slow_path;
- if (wr_mas->entry && (wr_mas->node_end < node_slots - 1) &&
+ if (wr_mas->entry && (wr_mas->node_end < mt_slots[wr_mas->type] - 1) &&
(mas->offset == wr_mas->node_end) && mas_wr_append(wr_mas)) {
if (!wr_mas->content || !wr_mas->entry)
mas_update_gap(mas);
_
Patches currently in -mm which might be from zhangpeng.00@xxxxxxxxxxxxx are
radix-tree-move-declarations-to-header-fix.patch
maple_tree-fix-potential-out-of-bounds-access-in-mas_wr_end_piv.patch
maple_tree-rework-mtree_alloc_rangerrange.patch
maple_tree-drop-mas_rev_alloc-and-mas_fill_gap.patch
maple_tree-fix-the-arguments-to-__must_hold.patch
maple_tree-simplify-mas_is_span_wr.patch
maple_tree-make-the-code-symmetrical-in-mas_wr_extend_null.patch
maple_tree-add-mas_wr_new_end-to-calculate-new_end-accurately.patch
maple_tree-add-comments-and-some-minor-cleanups-to-mas_wr_append.patch
maple_tree-rework-mas_wr_slot_store-to-be-cleaner-and-more-efficient.patch
maple_tree-simplify-and-clean-up-mas_wr_node_store.patch
maple_tree-relocate-the-declaration-of-mas_empty_area_rev.patch
