maple_tree: add testing for restoring maple state to active

Restoring maple status to ma_active on overflow/underflow when mas->node
was NULL could have happened in the past, but was masked by a bug in
mas_walk().  Add test cases that triggered the bug when the node was
mas->node prior to fixing the maple state setup.

Add a few extra tests around restoring the active maple status.

Link: https://lore.kernel.org/all/202506191556.6bfc7b93-lkp@intel.com/
Link: https://lkml.kernel.org/r/20250624154823.52221-2-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index 13e2a10d7554d6b1de5ffbda59f3a5bc4039a8c8..cb3936595b0d56a9682ff100eba54693a1427829 100644 (file)
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -3177,6 +3177,7 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
        void *entry, *ptr = (void *) 0x1234500;
        void *ptr2 = &ptr;
        void *ptr3 = &ptr2;
+       unsigned long index;
 
        /* Check MAS_ROOT First */
        mtree_store_range(mt, 0, 0, ptr, GFP_KERNEL);
@@ -3706,6 +3707,37 @@ static noinline void __init check_state_handling(struct maple_tree *mt)
        MT_BUG_ON(mt, mas.last != 0x1fff);
        MT_BUG_ON(mt, !mas_is_active(&mas));
 
+       mas_unlock(&mas);
+       mtree_destroy(mt);
+
+       mt_init_flags(mt, MT_FLAGS_ALLOC_RANGE);
+       mas_lock(&mas);
+       for (int count = 0; count < 30; count++) {
+               mas_set(&mas, count);
+               mas_store_gfp(&mas, xa_mk_value(count), GFP_KERNEL);
+       }
+
+       /* Ensure mas_find works with MA_UNDERFLOW */
+       mas_set(&mas, 0);
+       entry = mas_walk(&mas);
+       mas_set(&mas, 0);
+       mas_prev(&mas, 0);
+       MT_BUG_ON(mt, mas.status != ma_underflow);
+       MT_BUG_ON(mt, mas_find(&mas, ULONG_MAX) != entry);
+
+       /* Restore active on mas_next */
+       entry = mas_next(&mas, ULONG_MAX);
+       index = mas.index;
+       mas_prev(&mas, index);
+       MT_BUG_ON(mt, mas.status != ma_underflow);
+       MT_BUG_ON(mt, mas_next(&mas, ULONG_MAX) != entry);
+
+       /* Ensure overflow -> active works */
+       mas_prev(&mas, 0);
+       mas_next(&mas, index - 1);
+       MT_BUG_ON(mt, mas.status != ma_overflow);
+       MT_BUG_ON(mt, mas_next(&mas, ULONG_MAX) != entry);
+
        mas_unlock(&mas);
 }