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 --- This is a modified backport as the patch to fix this in upstream does not apply to 6.6 because the node_end field was moved from the ma_wr_state to the ma_state after 6.6.
lib/maple_tree.c | 6 ++++++ tools/testing/radix-tree/maple.c | 2 +- 2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/lib/maple_tree.c b/lib/maple_tree.c index bb24d84a4922f..5950d0c0e0f69 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -5501,6 +5501,12 @@ 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) && ((!mt_in_rcu(mas->tree)) + || (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);