maple_tree: make maple state reusable after mas_empty_area()

commit 0257d9908d38c0b1669af4bb1bc4dbca1f273fe6 upstream.

Make mas->min and mas->max point to a node range instead of a leaf entry
range.  This allows mas to still be usable after mas_empty_area() returns.
Users would get unexpected results from other operations on the maple
state after calling the affected function.

For example, x86 MAP_32BIT mmap() acts as if there is no suitable gap when
there should be one.

Link: https://lkml.kernel.org/r/20230505145829.74574-1-zhangpeng.00@bytedance.com
Fixes: 6b5ffa9b4f4f ("Maple Tree: add new data structure")
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reported-by: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Reported-by: Tad <support@spotco.us>
Reported-by: Michael Keyes <mgkeyes@vigovproductions.net>
Link: https://lore.kernel.org/linux-mm/32f156ba80010fd97dbaf0a0cdfc84366608624d.camel@intel.com/
Link: https://lore.kernel.org/linux-mm/e6108286ac025c268964a7ead3aab9899f9bc6e9.camel@spotco.us/
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Tested-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 9fe25ce9937b81a1ef675353018c84363de235c3..b72268848ade1407e5d6c344e7324d3542d741b1 100644 (file)
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5338,15 +5338,9 @@ int mas_empty_area(struct ma_state *mas, unsigned long min,
 
        mt = mte_node_type(mas->node);
        pivots = ma_pivots(mas_mn(mas), mt);
-       if (offset)
-               mas->min = pivots[offset - 1] + 1;
-
-       if (offset < mt_pivots[mt])
-               mas->max = pivots[offset];
-
-       if (mas->index < mas->min)
-               mas->index = mas->min;
-
+       min = mas_safe_min(mas, pivots, offset);
+       if (mas->index < min)
+               mas->index = min;
        mas->last = mas->index + size - 1;
        return 0;
 }