XArray updates for 4.20-rc7

Two bugfixes, each with test-suite updates, two improvements to the
 test-suite without associated bugs, and one patch adding a missing API.
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Merge tag 'xarray-4.20-rc7' of git://git.infradead.org/users/willy/linux-dax

Pull XArray fixes from Matthew Wilcox:
 "Two bugfixes, each with test-suite updates, two improvements to the
  test-suite without associated bugs, and one patch adding a missing
  API"

* tag 'xarray-4.20-rc7' of git://git.infradead.org/users/willy/linux-dax:
  XArray: Fix xa_alloc when id exceeds max
  XArray tests: Check iterating over multiorder entries
  XArray tests: Handle larger indices more elegantly
  XArray: Add xa_cmpxchg_irq and xa_cmpxchg_bh
  radix tree: Don't return retry entries from lookup

Documentation/core-api/xarray.rst

@@ -187,6 +187,8 @@ Takes xa_lock internally:
  * :c:func:`xa_erase_bh`
  * :c:func:`xa_erase_irq`
  * :c:func:`xa_cmpxchg`
+ * :c:func:`xa_cmpxchg_bh`
+ * :c:func:`xa_cmpxchg_irq`
  * :c:func:`xa_store_range`
  * :c:func:`xa_alloc`
  * :c:func:`xa_alloc_bh`
@@ -263,7 +265,8 @@ using :c:func:`xa_lock_irqsave` in both the interrupt handler and process
 context, or :c:func:`xa_lock_irq` in process context and :c:func:`xa_lock`
 in the interrupt handler.  Some of the more common patterns have helper
 functions such as :c:func:`xa_store_bh`, :c:func:`xa_store_irq`,
-:c:func:`xa_erase_bh` and :c:func:`xa_erase_irq`.
+:c:func:`xa_erase_bh`, :c:func:`xa_erase_irq`, :c:func:`xa_cmpxchg_bh`
+and :c:func:`xa_cmpxchg_irq`.
 
 Sometimes you need to protect access to the XArray with a mutex because
 that lock sits above another mutex in the locking hierarchy.  That does

include/linux/xarray.h

@@ -553,6 +553,60 @@ static inline void *xa_cmpxchg(struct xarray *xa, unsigned long index,
 	return curr;
 }
 
+/**
+ * xa_cmpxchg_bh() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_cmpxchg() except it disables softirqs
+ * while holding the array lock.
+ *
+ * Context: Any context.  Takes and releases the xa_lock while
+ * disabling softirqs.  May sleep if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg_bh(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock_bh(xa);
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+	xa_unlock_bh(xa);
+
+	return curr;
+}
+
+/**
+ * xa_cmpxchg_irq() - Conditionally replace an entry in the XArray.
+ * @xa: XArray.
+ * @index: Index into array.
+ * @old: Old value to test against.
+ * @entry: New value to place in array.
+ * @gfp: Memory allocation flags.
+ *
+ * This function is like calling xa_cmpxchg() except it disables interrupts
+ * while holding the array lock.
+ *
+ * Context: Process context.  Takes and releases the xa_lock while
+ * disabling interrupts.  May sleep if the @gfp flags permit.
+ * Return: The old value at this index or xa_err() if an error happened.
+ */
+static inline void *xa_cmpxchg_irq(struct xarray *xa, unsigned long index,
+			void *old, void *entry, gfp_t gfp)
+{
+	void *curr;
+
+	xa_lock_irq(xa);
+	curr = __xa_cmpxchg(xa, index, old, entry, gfp);
+	xa_unlock_irq(xa);
+
+	return curr;
+}
+
 /**
  * xa_insert() - Store this entry in the XArray unless another entry is
  *			already present.

lib/radix-tree.c

@@ -784,11 +784,11 @@ void *__radix_tree_lookup(const struct radix_tree_root *root,
 	while (radix_tree_is_internal_node(node)) {
 		unsigned offset;
 
-		if (node == RADIX_TREE_RETRY)
-			goto restart;
 		parent = entry_to_node(node);
 		offset = radix_tree_descend(parent, &node, index);
 		slot = parent->slots + offset;
+		if (node == RADIX_TREE_RETRY)
+			goto restart;
 		if (parent->shift == 0)
 			break;
 	}

lib/test_xarray.c

@@ -28,23 +28,28 @@ void xa_dump(const struct xarray *xa) { }
 } while (0)
 #endif
 
+static void *xa_mk_index(unsigned long index)
+{
+	return xa_mk_value(index & LONG_MAX);
+}
+
 static void *xa_store_index(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
-	return xa_store(xa, index, xa_mk_value(index & LONG_MAX), gfp);
+	return xa_store(xa, index, xa_mk_index(index), gfp);
 }
 
 static void xa_alloc_index(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
 	u32 id = 0;
 
-	XA_BUG_ON(xa, xa_alloc(xa, &id, UINT_MAX, xa_mk_value(index & LONG_MAX),
+	XA_BUG_ON(xa, xa_alloc(xa, &id, UINT_MAX, xa_mk_index(index),
 				gfp) != 0);
 	XA_BUG_ON(xa, id != index);
 }
 
 static void xa_erase_index(struct xarray *xa, unsigned long index)
 {
-	XA_BUG_ON(xa, xa_erase(xa, index) != xa_mk_value(index & LONG_MAX));
+	XA_BUG_ON(xa, xa_erase(xa, index) != xa_mk_index(index));
 	XA_BUG_ON(xa, xa_load(xa, index) != NULL);
 }
 
@@ -118,7 +123,7 @@ static noinline void check_xas_retry(struct xarray *xa)
 
 	xas_set(&xas, 0);
 	xas_for_each(&xas, entry, ULONG_MAX) {
-		xas_store(&xas, xa_mk_value(xas.xa_index));
+		xas_store(&xas, xa_mk_index(xas.xa_index));
 	}
 	xas_unlock(&xas);
 
@@ -196,7 +201,7 @@ static noinline void check_xa_mark_1(struct xarray *xa, unsigned long index)
 		XA_BUG_ON(xa, xa_store_index(xa, index + 2, GFP_KERNEL));
 		xa_set_mark(xa, index + 2, XA_MARK_1);
 		XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL));
-		xa_store_order(xa, index, order, xa_mk_value(index),
+		xa_store_order(xa, index, order, xa_mk_index(index),
 				GFP_KERNEL);
 		for (i = base; i < next; i++) {
 			XA_STATE(xas, xa, i);
@@ -405,7 +410,7 @@ static noinline void check_xas_erase(struct xarray *xa)
 			xas_set(&xas, j);
 			do {
 				xas_lock(&xas);
-				xas_store(&xas, xa_mk_value(j));
+				xas_store(&xas, xa_mk_index(j));
 				xas_unlock(&xas);
 			} while (xas_nomem(&xas, GFP_KERNEL));
 		}
@@ -423,7 +428,7 @@ static noinline void check_xas_erase(struct xarray *xa)
 		xas_set(&xas, 0);
 		j = i;
 		xas_for_each(&xas, entry, ULONG_MAX) {
-			XA_BUG_ON(xa, entry != xa_mk_value(j));
+			XA_BUG_ON(xa, entry != xa_mk_index(j));
 			xas_store(&xas, NULL);
 			j++;
 		}
@@ -440,17 +445,17 @@ static noinline void check_multi_store_1(struct xarray *xa, unsigned long index,
 	unsigned long min = index & ~((1UL << order) - 1);
 	unsigned long max = min + (1UL << order);
 
-	xa_store_order(xa, index, order, xa_mk_value(index), GFP_KERNEL);
+	xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);
-	XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_value(index));
+	XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_index(index));
-	XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_value(index));
+	XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_index(index));
 	XA_BUG_ON(xa, xa_load(xa, max) != NULL);
 	XA_BUG_ON(xa, xa_load(xa, min - 1) != NULL);
 
 	xas_lock(&xas);
-	XA_BUG_ON(xa, xas_store(&xas, xa_mk_value(min)) != xa_mk_value(index));
+	XA_BUG_ON(xa, xas_store(&xas, xa_mk_index(min)) != xa_mk_index(index));
 	xas_unlock(&xas);
-	XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_value(min));
+	XA_BUG_ON(xa, xa_load(xa, min) != xa_mk_index(min));
-	XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_value(min));
+	XA_BUG_ON(xa, xa_load(xa, max - 1) != xa_mk_index(min));
 	XA_BUG_ON(xa, xa_load(xa, max) != NULL);
 	XA_BUG_ON(xa, xa_load(xa, min - 1) != NULL);
 
@@ -471,6 +476,32 @@ static noinline void check_multi_store_2(struct xarray *xa, unsigned long index,
 	xas_unlock(&xas);
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
+
+static noinline void check_multi_store_3(struct xarray *xa, unsigned long index,
+		unsigned int order)
+{
+	XA_STATE(xas, xa, 0);
+	void *entry;
+	int n = 0;
+
+	xa_store_order(xa, index, order, xa_mk_index(index), GFP_KERNEL);
+
+	xas_lock(&xas);
+	xas_for_each(&xas, entry, ULONG_MAX) {
+		XA_BUG_ON(xa, entry != xa_mk_index(index));
+		n++;
+	}
+	XA_BUG_ON(xa, n != 1);
+	xas_set(&xas, index + 1);
+	xas_for_each(&xas, entry, ULONG_MAX) {
+		XA_BUG_ON(xa, entry != xa_mk_index(index));
+		n++;
+	}
+	XA_BUG_ON(xa, n != 2);
+	xas_unlock(&xas);
+
+	xa_destroy(xa);
+}
 #endif
 
 static noinline void check_multi_store(struct xarray *xa)
@@ -523,15 +554,15 @@ static noinline void check_multi_store(struct xarray *xa)
 
 	for (i = 0; i < max_order; i++) {
 		for (j = 0; j < max_order; j++) {
-			xa_store_order(xa, 0, i, xa_mk_value(i), GFP_KERNEL);
+			xa_store_order(xa, 0, i, xa_mk_index(i), GFP_KERNEL);
-			xa_store_order(xa, 0, j, xa_mk_value(j), GFP_KERNEL);
+			xa_store_order(xa, 0, j, xa_mk_index(j), GFP_KERNEL);
 
 			for (k = 0; k < max_order; k++) {
 				void *entry = xa_load(xa, (1UL << k) - 1);
 				if ((i < k) && (j < k))
 					XA_BUG_ON(xa, entry != NULL);
 				else
-					XA_BUG_ON(xa, entry != xa_mk_value(j));
+					XA_BUG_ON(xa, entry != xa_mk_index(j));
 			}
 
 			xa_erase(xa, 0);
@@ -545,6 +576,11 @@ static noinline void check_multi_store(struct xarray *xa)
 		check_multi_store_1(xa, (1UL << i) + 1, i);
 	}
 	check_multi_store_2(xa, 4095, 9);
+
+	for (i = 1; i < 20; i++) {
+		check_multi_store_3(xa, 0, i);
+		check_multi_store_3(xa, 1UL << i, i);
+	}
 #endif
 }
 
@@ -587,16 +623,25 @@ static noinline void check_xa_alloc(void)
 	xa_destroy(&xa0);
 
 	id = 0xfffffffeU;
-	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_value(0),
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_index(id),
 				GFP_KERNEL) != 0);
 	XA_BUG_ON(&xa0, id != 0xfffffffeU);
-	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_value(0),
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_index(id),
 				GFP_KERNEL) != 0);
 	XA_BUG_ON(&xa0, id != 0xffffffffU);
-	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_value(0),
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_index(id),
 				GFP_KERNEL) != -ENOSPC);
 	XA_BUG_ON(&xa0, id != 0xffffffffU);
 	xa_destroy(&xa0);
+
+	id = 10;
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, 5, xa_mk_index(id),
+				GFP_KERNEL) != -ENOSPC);
+	XA_BUG_ON(&xa0, xa_store_index(&xa0, 3, GFP_KERNEL) != 0);
+	XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, 5, xa_mk_index(id),
+				GFP_KERNEL) != -ENOSPC);
+	xa_erase_index(&xa0, 3);
+	XA_BUG_ON(&xa0, !xa_empty(&xa0));
 }
 
 static noinline void __check_store_iter(struct xarray *xa, unsigned long start,
@@ -610,11 +655,11 @@ retry:
 	xas_lock(&xas);
 	xas_for_each_conflict(&xas, entry) {
 		XA_BUG_ON(xa, !xa_is_value(entry));
-		XA_BUG_ON(xa, entry < xa_mk_value(start));
+		XA_BUG_ON(xa, entry < xa_mk_index(start));
-		XA_BUG_ON(xa, entry > xa_mk_value(start + (1UL << order) - 1));
+		XA_BUG_ON(xa, entry > xa_mk_index(start + (1UL << order) - 1));
 		count++;
 	}
-	xas_store(&xas, xa_mk_value(start));
+	xas_store(&xas, xa_mk_index(start));
 	xas_unlock(&xas);
 	if (xas_nomem(&xas, GFP_KERNEL)) {
 		count = 0;
@@ -622,9 +667,9 @@ retry:
 	}
 	XA_BUG_ON(xa, xas_error(&xas));
 	XA_BUG_ON(xa, count != present);
-	XA_BUG_ON(xa, xa_load(xa, start) != xa_mk_value(start));
+	XA_BUG_ON(xa, xa_load(xa, start) != xa_mk_index(start));
 	XA_BUG_ON(xa, xa_load(xa, start + (1UL << order) - 1) !=
-			xa_mk_value(start));
+			xa_mk_index(start));
 	xa_erase_index(xa, start);
 }
 
@@ -703,7 +748,7 @@ static noinline void check_multi_find_2(struct xarray *xa)
 		for (j = 0; j < index; j++) {
 			XA_STATE(xas, xa, j + index);
 			xa_store_index(xa, index - 1, GFP_KERNEL);
-			xa_store_order(xa, index, i, xa_mk_value(index),
+			xa_store_order(xa, index, i, xa_mk_index(index),
 					GFP_KERNEL);
 			rcu_read_lock();
 			xas_for_each(&xas, entry, ULONG_MAX) {
@@ -778,7 +823,7 @@ static noinline void check_find_2(struct xarray *xa)
 		j = 0;
 		index = 0;
 		xa_for_each(xa, entry, index, ULONG_MAX, XA_PRESENT) {
-			XA_BUG_ON(xa, xa_mk_value(index) != entry);
+			XA_BUG_ON(xa, xa_mk_index(index) != entry);
 			XA_BUG_ON(xa, index != j++);
 		}
 	}
@@ -786,10 +831,34 @@ static noinline void check_find_2(struct xarray *xa)
 	xa_destroy(xa);
 }
 
+static noinline void check_find_3(struct xarray *xa)
+{
+	XA_STATE(xas, xa, 0);
+	unsigned long i, j, k;
+	void *entry;
+
+	for (i = 0; i < 100; i++) {
+		for (j = 0; j < 100; j++) {
+			for (k = 0; k < 100; k++) {
+				xas_set(&xas, j);
+				xas_for_each_marked(&xas, entry, k, XA_MARK_0)
+					;
+				if (j > k)
+					XA_BUG_ON(xa,
+						xas.xa_node != XAS_RESTART);
+			}
+		}
+		xa_store_index(xa, i, GFP_KERNEL);
+		xa_set_mark(xa, i, XA_MARK_0);
+	}
+	xa_destroy(xa);
+}
+
 static noinline void check_find(struct xarray *xa)
 {
 	check_find_1(xa);
 	check_find_2(xa);
+	check_find_3(xa);
 	check_multi_find(xa);
 	check_multi_find_2(xa);
 }
@@ -829,11 +898,11 @@ static noinline void check_find_entry(struct xarray *xa)
 			for (index = 0; index < (1UL << (order + 5));
 			     index += (1UL << order)) {
 				xa_store_order(xa, index, order,
-						xa_mk_value(index), GFP_KERNEL);
+						xa_mk_index(index), GFP_KERNEL);
 				XA_BUG_ON(xa, xa_load(xa, index) !=
-						xa_mk_value(index));
+						xa_mk_index(index));
 				XA_BUG_ON(xa, xa_find_entry(xa,
-						xa_mk_value(index)) != index);
+						xa_mk_index(index)) != index);
 			}
 			XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
 			xa_destroy(xa);
@@ -844,7 +913,7 @@ static noinline void check_find_entry(struct xarray *xa)
 	XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
 	xa_store_index(xa, ULONG_MAX, GFP_KERNEL);
 	XA_BUG_ON(xa, xa_find_entry(xa, xa) != -1);
-	XA_BUG_ON(xa, xa_find_entry(xa, xa_mk_value(LONG_MAX)) != -1);
+	XA_BUG_ON(xa, xa_find_entry(xa, xa_mk_index(ULONG_MAX)) != -1);
 	xa_erase_index(xa, ULONG_MAX);
 	XA_BUG_ON(xa, !xa_empty(xa));
 }
@@ -864,7 +933,7 @@ static noinline void check_move_small(struct xarray *xa, unsigned long idx)
 			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
 		XA_BUG_ON(xa, xas.xa_index != i);
 		if (i == 0 || i == idx)
-			XA_BUG_ON(xa, entry != xa_mk_value(i));
+			XA_BUG_ON(xa, entry != xa_mk_index(i));
 		else
 			XA_BUG_ON(xa, entry != NULL);
 	}
@@ -878,7 +947,7 @@ static noinline void check_move_small(struct xarray *xa, unsigned long idx)
 			XA_BUG_ON(xa, xas.xa_node == XAS_RESTART);
 		XA_BUG_ON(xa, xas.xa_index != i);
 		if (i == 0 || i == idx)
-			XA_BUG_ON(xa, entry != xa_mk_value(i));
+			XA_BUG_ON(xa, entry != xa_mk_index(i));
 		else
 			XA_BUG_ON(xa, entry != NULL);
 	} while (i > 0);
@@ -909,7 +978,7 @@ static noinline void check_move(struct xarray *xa)
 	do {
 		void *entry = xas_prev(&xas);
 		i--;
-		XA_BUG_ON(xa, entry != xa_mk_value(i));
+		XA_BUG_ON(xa, entry != xa_mk_index(i));
 		XA_BUG_ON(xa, i != xas.xa_index);
 	} while (i != 0);
 
@@ -918,7 +987,7 @@ static noinline void check_move(struct xarray *xa)
 
 	do {
 		void *entry = xas_next(&xas);
-		XA_BUG_ON(xa, entry != xa_mk_value(i));
+		XA_BUG_ON(xa, entry != xa_mk_index(i));
 		XA_BUG_ON(xa, i != xas.xa_index);
 		i++;
 	} while (i < (1 << 16));
@@ -934,7 +1003,7 @@ static noinline void check_move(struct xarray *xa)
 		void *entry = xas_prev(&xas);
 		i--;
 		if ((i < (1 << 8)) || (i >= (1 << 15)))
-			XA_BUG_ON(xa, entry != xa_mk_value(i));
+			XA_BUG_ON(xa, entry != xa_mk_index(i));
 		else
 			XA_BUG_ON(xa, entry != NULL);
 		XA_BUG_ON(xa, i != xas.xa_index);
@@ -946,7 +1015,7 @@ static noinline void check_move(struct xarray *xa)
 	do {
 		void *entry = xas_next(&xas);
 		if ((i < (1 << 8)) || (i >= (1 << 15)))
-			XA_BUG_ON(xa, entry != xa_mk_value(i));
+			XA_BUG_ON(xa, entry != xa_mk_index(i));
 		else
 			XA_BUG_ON(xa, entry != NULL);
 		XA_BUG_ON(xa, i != xas.xa_index);
@@ -976,7 +1045,7 @@ static noinline void xa_store_many_order(struct xarray *xa,
 		if (xas_error(&xas))
 			goto unlock;
 		for (i = 0; i < (1U << order); i++) {
-			XA_BUG_ON(xa, xas_store(&xas, xa_mk_value(index + i)));
+			XA_BUG_ON(xa, xas_store(&xas, xa_mk_index(index + i)));
 			xas_next(&xas);
 		}
 unlock:
@@ -1031,9 +1100,9 @@ static noinline void check_create_range_4(struct xarray *xa,
 		if (xas_error(&xas))
 			goto unlock;
 		for (i = 0; i < (1UL << order); i++) {
-			void *old = xas_store(&xas, xa_mk_value(base + i));
+			void *old = xas_store(&xas, xa_mk_index(base + i));
 			if (xas.xa_index == index)
-				XA_BUG_ON(xa, old != xa_mk_value(base + i));
+				XA_BUG_ON(xa, old != xa_mk_index(base + i));
 			else
 				XA_BUG_ON(xa, old != NULL);
 			xas_next(&xas);
@@ -1085,10 +1154,10 @@ static noinline void __check_store_range(struct xarray *xa, unsigned long first,
 		unsigned long last)
 {
 #ifdef CONFIG_XARRAY_MULTI
-	xa_store_range(xa, first, last, xa_mk_value(first), GFP_KERNEL);
+	xa_store_range(xa, first, last, xa_mk_index(first), GFP_KERNEL);
 
-	XA_BUG_ON(xa, xa_load(xa, first) != xa_mk_value(first));
+	XA_BUG_ON(xa, xa_load(xa, first) != xa_mk_index(first));
-	XA_BUG_ON(xa, xa_load(xa, last) != xa_mk_value(first));
+	XA_BUG_ON(xa, xa_load(xa, last) != xa_mk_index(first));
 	XA_BUG_ON(xa, xa_load(xa, first - 1) != NULL);
 	XA_BUG_ON(xa, xa_load(xa, last + 1) != NULL);
 
@@ -1195,7 +1264,7 @@ static noinline void check_account(struct xarray *xa)
 		XA_BUG_ON(xa, xas.xa_node->nr_values != 0);
 		rcu_read_unlock();
 
-		xa_store_order(xa, 1 << order, order, xa_mk_value(1 << order),
+		xa_store_order(xa, 1 << order, order, xa_mk_index(1UL << order),
 				GFP_KERNEL);
 		XA_BUG_ON(xa, xas.xa_node->count != xas.xa_node->nr_values * 2);
 

lib/xarray.c

@@ -1131,7 +1131,7 @@ void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
 		entry = xa_head(xas->xa);
 		xas->xa_node = NULL;
 		if (xas->xa_index > max_index(entry))
-			goto bounds;
+			goto out;
 		if (!xa_is_node(entry)) {
 			if (xa_marked(xas->xa, mark))
 				return entry;
@@ -1180,11 +1180,9 @@ void *xas_find_marked(struct xa_state *xas, unsigned long max, xa_mark_t mark)
 	}
 
 out:
-	if (!max)
+	if (xas->xa_index > max)
 		goto max;
-bounds:
+	return set_bounds(xas);
-	xas->xa_node = XAS_BOUNDS;
-	return NULL;
 max:
 	xas->xa_node = XAS_RESTART;
 	return NULL;

mm/shmem.c

@@ -661,9 +661,7 @@ static int shmem_free_swap(struct address_space *mapping,
 {
 	void *old;
 
-	xa_lock_irq(&mapping->i_pages);
+	old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0);
-	old = __xa_cmpxchg(&mapping->i_pages, index, radswap, NULL, 0);
-	xa_unlock_irq(&mapping->i_pages);
 	if (old != radswap)
 		return -ENOENT;
 	free_swap_and_cache(radix_to_swp_entry(radswap));

tools/testing/radix-tree/Makefile

@@ -7,6 +7,7 @@ LDLIBS+= -lpthread -lurcu
 TARGETS = main idr-test multiorder xarray
 CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o bitmap.o
 OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
+	 regression4.o \
 	 tag_check.o multiorder.o idr-test.o iteration_check.o benchmark.o
 
 ifndef SHIFT

tools/testing/radix-tree/main.c

@@ -308,6 +308,7 @@ int main(int argc, char **argv)
 	regression1_test();
 	regression2_test();
 	regression3_test();
+	regression4_test();
 	iteration_test(0, 10 + 90 * long_run);
 	iteration_test(7, 10 + 90 * long_run);
 	single_thread_tests(long_run);

tools/testing/radix-tree/regression.h

@@ -5,5 +5,6 @@
 void regression1_test(void);
 void regression2_test(void);
 void regression3_test(void);
+void regression4_test(void);
 
 #endif

tools/testing/radix-tree/regression4.c

@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/radix-tree.h>
+#include <linux/rcupdate.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <assert.h>
+
+#include "regression.h"
+
+static pthread_barrier_t worker_barrier;
+static int obj0, obj1;
+static RADIX_TREE(mt_tree, GFP_KERNEL);
+
+static void *reader_fn(void *arg)
+{
+	int i;
+	void *entry;
+
+	rcu_register_thread();
+	pthread_barrier_wait(&worker_barrier);
+
+	for (i = 0; i < 1000000; i++) {
+		rcu_read_lock();
+		entry = radix_tree_lookup(&mt_tree, 0);
+		rcu_read_unlock();
+		if (entry != &obj0) {
+			printf("iteration %d bad entry = %p\n", i, entry);
+			abort();
+		}
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+static void *writer_fn(void *arg)
+{
+	int i;
+
+	rcu_register_thread();
+	pthread_barrier_wait(&worker_barrier);
+
+	for (i = 0; i < 1000000; i++) {
+		radix_tree_insert(&mt_tree, 1, &obj1);
+		radix_tree_delete(&mt_tree, 1);
+	}
+
+	rcu_unregister_thread();
+
+	return NULL;
+}
+
+void regression4_test(void)
+{
+	pthread_t reader, writer;
+
+	printv(1, "regression test 4 starting\n");
+
+	radix_tree_insert(&mt_tree, 0, &obj0);
+	pthread_barrier_init(&worker_barrier, NULL, 2);
+
+	if (pthread_create(&reader, NULL, reader_fn, NULL) ||
+	    pthread_create(&writer, NULL, writer_fn, NULL)) {
+		perror("pthread_create");
+		exit(1);
+	}
+
+	if (pthread_join(reader, NULL) || pthread_join(writer, NULL)) {
+		perror("pthread_join");
+		exit(1);
+	}
+
+	printv(1, "regression test 4 passed\n");
+}