linux-kernel - [PATCH] maple_tree: Fix mas_empty_area_rev() search exhaustion at root node

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Date:   Tue, 12 Jul 2022 01:50:36 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>
Subject: [PATCH] maple_tree: Fix mas_empty_area_rev() search exhaustion at
 root node

When the possibilities of finding a gap are exhausted at the root node,
the error code was not returned which results in returning a range that
is currently occupied.  Add the necessary check for the error code and
return to the caller.

Reported-by: Alexander Gordeev <agordeev@...ux.ibm.com>
Fixes: d0aac5e48048 (Maple Tree: add new data structure)
Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 lib/maple_tree.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index 9dc4ffff18d0..14e9ab14c1da 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -5287,6 +5287,9 @@ int mas_empty_area_rev(struct ma_state *mas, unsigned long min,
 		}
 	}
 
+	if (mas_is_err(mas))
+		return xa_err(mas->node);
+
 	if (unlikely(mas->offset == MAPLE_NODE_SLOTS))
 		return -EBUSY;
 
-- 
2.35.1