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@vger.kernel.org # 6.6+ Signed-off-by: Sidhartha Kumar sidhartha.kumar@oracle.com
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@oracle.com...
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);