The patch titled
Subject: maple_tree: Fix use of node for global range in mas_wr_spanning_store()
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 use of node for global range in mas_wr_spanning_store()
Date: Wed, 6 Jul 2022 02:05:37 +0000
When writing a range with a NULL which expands to 0 - ULONG_MAX, don't use
a node to store this value. Instead, call mas_new_root() which will set
the tree pointer to NULL and free all the nodes.
Fix a comment for the allocations in mas_wr_spanning_store().
Add mas_node_count_gfp() and use it to clean up mas_preallocate().
Clean up mas_preallocate() and ensure the ma_state is safe on return.
Update maple_tree.h to set alloc = NULL.
Link: https://lkml.kernel.org/r/20220706020526.1869453-1-Liam.Howlett@xxxxxxxxxx
Fixes: d0aac5e48048 (Maple Tree: add new data structure)
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/maple_tree.h | 1 +
lib/maple_tree.c | 34 +++++++++++++++++++++++++++-------
2 files changed, 28 insertions(+), 7 deletions(-)
--- a/include/linux/maple_tree.h~maple-tree-add-new-data-structure-fix-3
+++ a/include/linux/maple_tree.h
@@ -434,6 +434,7 @@ struct ma_wr_state {
.node = MAS_START, \
.min = 0, \
.max = ULONG_MAX, \
+ .alloc = NULL, \
}
#define MA_WR_STATE(name, ma_state, wr_entry) \
--- a/lib/maple_tree.c~maple-tree-add-new-data-structure-fix-3
+++ a/lib/maple_tree.c
@@ -1293,18 +1293,32 @@ static inline void mas_free(struct ma_st
* there is not enough nodes.
* @mas: The maple state
* @count: The number of nodes needed
+ * @gfp: the gfp flags
*/
-static void mas_node_count(struct ma_state *mas, int count)
+static void mas_node_count_gfp(struct ma_state *mas, int count, gfp_t gfp)
{
unsigned long allocated = mas_allocated(mas);
if (allocated < count) {
mas_set_alloc_req(mas, count - allocated);
- mas_alloc_nodes(mas, GFP_NOWAIT | __GFP_NOWARN);
+ mas_alloc_nodes(mas, gfp);
}
}
/*
+ * mas_node_count() - Check if enough nodes are allocated and request more if
+ * there is not enough nodes.
+ * @mas: The maple state
+ * @count: The number of nodes needed
+ *
+ * Note: Uses GFP_NOWAIT | __GFP_NOWARN for gfp flags.
+ */
+static void mas_node_count(struct ma_state *mas, int count)
+{
+ return mas_node_count_gfp(mas, count, GFP_NOWAIT | __GFP_NOWARN);
+}
+
+/*
* mas_start() - Sets up maple state for operations.
* @mas: The maple state.
*
@@ -3962,7 +3976,7 @@ static inline int mas_wr_spanning_store(
if (unlikely(!mas->index && mas->last == ULONG_MAX))
return mas_new_root(mas, wr_mas->entry);
/*
- * Node rebalancing may occur due to this store, so there may be two new
+ * Node rebalancing may occur due to this store, so there may be three new
* entries per level plus a new root.
*/
height = mas_mt_height(mas);
@@ -3995,6 +4009,12 @@ static inline int mas_wr_spanning_store(
mas->last = l_mas.last = r_mas.last;
}
+ /* expanding NULLs may make this cover the entire range */
+ if (!l_mas.index && r_mas.last == ULONG_MAX) {
+ mas_set_range(mas, 0, ULONG_MAX);
+ return mas_new_root(mas, wr_mas->entry);
+ }
+
memset(&b_node, 0, sizeof(struct maple_big_node));
/* Copy l_mas and store the value in b_node. */
mas_store_b_node(&l_wr_mas, &b_node, l_wr_mas.node_end);
@@ -5657,15 +5677,15 @@ int mas_preallocate(struct ma_state *mas
{
int ret;
- mas_set_alloc_req(mas, 1 + mas_mt_height(mas) * 3);
- mas_alloc_nodes(mas, gfp);
+ mas_node_count_gfp(mas, 1 + mas_mt_height(mas) * 3, gfp);
if (likely(!mas_is_err(mas)))
return 0;
mas_set_alloc_req(mas, 0);
- mas_destroy(mas);
ret = xa_err(mas->node);
- mas->node = MAS_START;
+ mas_reset(mas);
+ mas_destroy(mas);
+ mas_reset(mas);
return ret;
}
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
android-binder-fix-lockdep-check-on-clearing-vma.patch
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
lib-test_maple_tree-add-testing-for-maple-tree-fix-2.patch
mm-mlock-drop-dead-code-in-count_mm_mlocked_page_nr.patch
