On 12/13/23 12:50 PM, Sidhartha Kumar wrote:
mas_preallocate() defaults to requesting 1 node for preallocation and then
,depending on the type of store, will update the request variable. There
isn't a check for a slot store type, so slot stores are preallocating the
default 1 node. Slot stores do not require any additional nodes, so add a
check for the slot store case that will bypass node_count_gfp(). Update
the tests to reflect that slot stores do not require allocations.
User visible effects of this bug include increased memory usage from the
unneeded node that was allocated.
Fixes: 0b8bb544b1a7 ("maple_tree: update mas_preallocate() testing")
Cc: <stable@xxxxxxxxxxxxxxx> # 6.6+
Signed-off-by: Sidhartha Kumar <sidhartha.kumar@xxxxxxxxxx>
---
v1->v2:
fix coding style per Matthew and Andrew
use wr_mas->node_end to fix build error
When this is merged to mm-unstable could the following fixlet be applied to be
compatible with Liam's series[1]:
[1]:
https://lore.kernel.org/all/20231101171629.3612299-5-Liam.Howlett@xxxxxxxxxx/T/#mc0e5000f6de822182bf7579c230030c5ec4ec1a7
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 1130803b9d3f7..c9a970ea20dd5 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5477,7 +5477,7 @@ int mas_preallocate(struct ma_state *mas, void *entry,
gfp_t gfp)
node_size = mas_wr_new_end(&wr_mas);
/* Slot store, does not require additional nodes */
- if (node_size == wr_mas.node_end) {
+ if (node_size == mas->end) {
/* reuse node */
if (!mt_in_rcu(mas->tree))
return 0;
lib/maple_tree.c | 11 +++++++++++
tools/testing/radix-tree/maple.c | 2 +-
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index bb24d84a4922f..684689457d77f 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5501,6 +5501,17 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp)
mas_wr_end_piv(&wr_mas);
node_size = mas_wr_new_end(&wr_mas);
+
+ /* Slot store, does not require additional nodes */
+ if (node_size == wr_mas.node_end) {
+ /* reuse node */
+ if (!mt_in_rcu(mas->tree))
+ return 0;
+ /* shifting boundary */
+ if (wr_mas.offset_end - mas->offset == 1)
+ return 0;
+ }
+
if (node_size >= mt_slots[wr_mas.type]) {
/* Split, worst case for now. */
request = 1 + mas_mt_height(mas) * 2;
diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
index e5da1cad70baf..76a8990bb14e8 100644
--- a/tools/testing/radix-tree/maple.c
+++ b/tools/testing/radix-tree/maple.c
@@ -35538,7 +35538,7 @@ static noinline void __init check_prealloc(struct maple_tree *mt)
MT_BUG_ON(mt, mas_preallocate(&mas, ptr, GFP_KERNEL) != 0);
allocated = mas_allocated(&mas);
height = mas_mt_height(&mas);
- MT_BUG_ON(mt, allocated != 1);
+ MT_BUG_ON(mt, allocated != 0);
mas_store_prealloc(&mas, ptr);
MT_BUG_ON(mt, mas_allocated(&mas) != 0);
