The patch titled
Subject: maple_tree: fix 32b parent pointers
has been added to the -mm mm-unstable branch. Its filename is
maple-tree-add-new-data-structure-fix-3.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-new-data-structure-fix-3.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 Howlett <liam.howlett@xxxxxxxxxx>
Subject: maple_tree: fix 32b parent pointers
Date: Tue, 17 May 2022 15:22:20 +0000
32 bit parent pointers need an extra bit to account for increased slot
count. Update the constants and documentation to use the remaining high
bit.
Link: https://lkml.kernel.org/r/20220517152209.3486724-1-Liam.Howlett@xxxxxxxxxx
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/maple_tree.h | 2 +-
lib/maple_tree.c | 14 +++++++-------
2 files changed, 8 insertions(+), 8 deletions(-)
--- a/include/linux/maple_tree.h~maple-tree-add-new-data-structure-fix-3
+++ a/include/linux/maple_tree.h
@@ -37,7 +37,7 @@
#define MAPLE_NODE_SLOTS 63 /* 256 bytes including ->parent */
#define MAPLE_RANGE64_SLOTS 32 /* 256 bytes */
#define MAPLE_ARANGE64_SLOTS 21 /* 240 bytes */
-#define MAPLE_ARANGE64_META_MAX 22 /* Out of range for metadata */
+#define MAPLE_ARANGE64_META_MAX 31 /* Out of range for metadata */
#define MAPLE_ALLOC_SLOTS (MAPLE_NODE_SLOTS - 2)
#endif /* defined(CONFIG_64BIT) || defined(BUILD_VDSO32_64) */
--- a/lib/maple_tree.c~maple-tree-add-new-data-structure-fix-3
+++ a/lib/maple_tree.c
@@ -354,7 +354,7 @@ static inline bool mt_is_alloc(struct ma
/*
* The Parent Pointer
* Excluding root, the parent pointer is 256B aligned like all other tree nodes.
- * When storing a 32 or 64 bit values, the offset can fit into 4 bits. The 16
+ * When storing a 32 or 64 bit values, the offset can fit into 5 bits. The 16
* bit values need an extra bit to store the offset. This extra bit comes from
* a reuse of the last bit in the node type. This is possible by using bit 1 to
* indicate if bit 2 is part of the type or the slot.
@@ -366,19 +366,19 @@ static inline bool mt_is_alloc(struct ma
* 0x110 = 64 bit nodes
*
* Slot size and alignment
- * 0x??1 : Root
- * 0x?00 : 16 bit values, type in 0-1, slot in 2-6
- * 0x010 : 32 bit values, type in 0-2, slot in 3-6
- * 0x110 : 64 bit values, type in 0-2, slot in 3-6
+ * 0b??1 : Root
+ * 0b?00 : 16 bit values, type in 0-1, slot in 2-7
+ * 0b010 : 32 bit values, type in 0-2, slot in 3-7
+ * 0b110 : 64 bit values, type in 0-2, slot in 3-7
*/
#define MAPLE_PARENT_ROOT 0x01
#define MAPLE_PARENT_SLOT_SHIFT 0x03
-#define MAPLE_PARENT_SLOT_MASK 0x78
+#define MAPLE_PARENT_SLOT_MASK 0xF8
#define MAPLE_PARENT_16B_SLOT_SHIFT 0x02
-#define MAPLE_PARENT_16B_SLOT_MASK 0x7C
+#define MAPLE_PARENT_16B_SLOT_MASK 0xFC
#define MAPLE_PARENT_RANGE64 0x06
#define MAPLE_PARENT_RANGE32 0x04
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
maple-tree-add-new-data-structure-fix.patch
maple-tree-add-new-data-structure-fix-2.patch
maple-tree-add-new-data-structure-fix-3.patch
lib-test_maple_tree-add-testing-for-maple-tree-fix.patch
mm-start-tracking-vmas-with-maple-tree-fix-2.patch
mm-remove-the-vma-linked-list-fix.patch
