maple_tree: revise limit checks in mas_empty_area{_rev}()

Since the maple tree is inclusive in range, ensure that a range of 1 (min
= max) works for searching for a gap in either direction, and make sure
the size is at least 1 but not larger than the delta between min and max.

This commit also updates the testing.  Unfortunately there isn't a way to
safely update the tests and code without a test failure.

Link: https://lkml.kernel.org/r/20230518145544.1722059-26-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Peng Zhang <zhangpeng.00@bytedance.com>
Cc: David Binderman <dcb314@hotmail.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Vernon Yang <vernon2gm@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 21 insertions, 7 deletions

diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c
index 19b130c9ddde..f167d6ef8159 100644
--- a/lib/test_maple_tree.c
+++ b/lib/test_maple_tree.c
@@ -123,7 +123,7 @@ static noinline void __init check_mtree_alloc_rrange(struct maple_tree *mt,
 	unsigned long result = expected + 1;
 	int ret;
 
-	ret = mtree_alloc_rrange(mt, &result, ptr, size, start, end - 1,
+	ret = mtree_alloc_rrange(mt, &result, ptr, size, start, end,
 			GFP_KERNEL);
 	MT_BUG_ON(mt, ret != eret);
 	if (ret)
@@ -701,7 +701,7 @@ static noinline void __init check_alloc_rev_range(struct maple_tree *mt)
 		0,              /* Return value success. */
 
 		0x0,            /* Min */
-		0x565234AF1 << 12,    /* Max */
+		0x565234AF0 << 12,    /* Max */
 		0x3000,         /* Size */
 		0x565234AEE << 12,  /* max - 3. */
 		0,              /* Return value success. */
@@ -713,14 +713,14 @@ static noinline void __init check_alloc_rev_range(struct maple_tree *mt)
 		0,              /* Return value success. */
 
 		0x0,            /* Min */
-		0x7F36D510A << 12,    /* Max */
+		0x7F36D5109 << 12,    /* Max */
 		0x4000,         /* Size */
 		0x7F36D5106 << 12,    /* First rev hole of size 0x4000 */
 		0,              /* Return value success. */
 
 		/* Ascend test. */
 		0x0,
-		34148798629 << 12,
+		34148798628 << 12,
 		19 << 12,
 		34148797418 << 12,
 		0x0,
@@ -732,6 +732,12 @@ static noinline void __init check_alloc_rev_range(struct maple_tree *mt)
 		0x0,
 		-EBUSY,
 
+		/* Single space test. */
+		34148798725 << 12,
+		34148798725 << 12,
+		1 << 12,
+		34148798725 << 12,
+		0,
 	};
 
 	int i, range_count = ARRAY_SIZE(range);
@@ -780,9 +786,9 @@ static noinline void __init check_alloc_rev_range(struct maple_tree *mt)
 	mas_unlock(&mas);
 	for (i = 0; i < req_range_count; i += 5) {
 #if DEBUG_REV_RANGE
-		pr_debug("\tReverse request between %lu-%lu size %lu, should get %lu\n",
-				req_range[i] >> 12,
-				(req_range[i + 1] >> 12) - 1,
+		pr_debug("\tReverse request %d between %lu-%lu size %lu, should get %lu\n",
+				i, req_range[i] >> 12,
+				(req_range[i + 1] >> 12),
 				req_range[i+2] >> 12,
 				req_range[i+3] >> 12);
 #endif
@@ -798,6 +804,7 @@ static noinline void __init check_alloc_rev_range(struct maple_tree *mt)
 
 	mt_set_non_kernel(1);
 	mtree_erase(mt, 34148798727); /* create a deleted range. */
+	mtree_erase(mt, 34148798725);
 	check_mtree_alloc_rrange(mt, 0, 34359052173, 210253414,
 			34148798725, 0, mt);
 
@@ -901,6 +908,13 @@ static noinline void __init check_alloc_range(struct maple_tree *mt)
 		4503599618982063UL << 12,  /* Size */
 		34359052178 << 12,  /* Expected location */
 		-EBUSY,             /* Return failure. */
+
+		/* Test a single entry */
+		34148798648 << 12,		/* Min */
+		34148798648 << 12,		/* Max */
+		4096,			/* Size of 1 */
+		34148798648 << 12,	/* Location is the same as min/max */
+		0,			/* Success */
 	};
 	int i, range_count = ARRAY_SIZE(range);
 	int req_range_count = ARRAY_SIZE(req_range);