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Date:   Mon, 31 Jul 2023 12:41:20 -0400
From:   "Liam R. Howlett" <Liam.Howlett@Oracle.com>
To:     Peng Zhang <zhangpeng.00@bytedance.com>
Cc:     linux-doc@vger.kernel.org, linux-mm@kvack.org, avagin@gmail.com,
        npiggin@gmail.com, mathieu.desnoyers@efficios.com,
        peterz@infradead.org, michael.christie@oracle.com,
        surenb@google.com, brauner@kernel.org, willy@infradead.org,
        corbet@lwn.net, linux-fsdevel@vger.kernel.org,
        akpm@linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 05/11] maple_tree: Add test for mt_dup()
Message-ID: <20230731164120.3xfyoynxh5b6mja2@revolver>
Mail-Followup-To: "Liam R. Howlett" <Liam.Howlett@Oracle.com>,
        Peng Zhang <zhangpeng.00@bytedance.com>, linux-doc@vger.kernel.org,
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        mathieu.desnoyers@efficios.com, peterz@infradead.org,
        michael.christie@oracle.com, surenb@google.com, brauner@kernel.org,
        willy@infradead.org, corbet@lwn.net, linux-fsdevel@vger.kernel.org,
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* Peng Zhang <zhangpeng.00@bytedance.com> [230731 08:32]:
>=20
>=20
> =E5=9C=A8 2023/7/27 00:06, Liam R. Howlett =E5=86=99=E9=81=93:
> > * Peng Zhang <zhangpeng.00@bytedance.com> [230726 04:10]:
> > > Add test for mt_dup().
> > >=20
> > > Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
> > > ---
> > >   tools/testing/radix-tree/maple.c | 202 ++++++++++++++++++++++++++++=
+++
> > >   1 file changed, 202 insertions(+)
> > >=20
> > > diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-t=
ree/maple.c
> > > index e5da1cad70ba..3052e899e5df 100644
> > > --- a/tools/testing/radix-tree/maple.c
> > > +++ b/tools/testing/radix-tree/maple.c
> > > @@ -35857,6 +35857,204 @@ static noinline void __init check_locky(str=
uct maple_tree *mt)
> > >   	mt_clear_in_rcu(mt);
> > >   }
> > > +/*
> > > + * Compare two nodes and return 0 if they are the same, non-zero oth=
erwise.
> > > + */
> > > +static int __init compare_node(struct maple_enode *enode_a,
> > > +			       struct maple_enode *enode_b)
> > > +{
> > > +	struct maple_node *node_a, *node_b;
> > > +	struct maple_node a, b;
> > > +	void **slots_a, **slots_b; /* Do not use the rcu tag. */
> > > +	enum maple_type type;
> > > +	int i;
> > > +
> > > +	if (((unsigned long)enode_a & MAPLE_NODE_MASK) !=3D
> > > +	    ((unsigned long)enode_b & MAPLE_NODE_MASK)) {
> > > +		pr_err("The lower 8 bits of enode are different.\n");
> > > +		return -1;
> > > +	}
> > > +
> > > +	type =3D mte_node_type(enode_a);
> > > +	node_a =3D mte_to_node(enode_a);
> > > +	node_b =3D mte_to_node(enode_b);
> > > +	a =3D *node_a;
> > > +	b =3D *node_b;
> > > +
> > > +	/* Do not compare addresses. */
> > > +	if (ma_is_root(node_a) || ma_is_root(node_b)) {
> > > +		a.parent =3D (struct maple_pnode *)((unsigned long)a.parent &
> > > +						  MA_ROOT_PARENT);
> > > +		b.parent =3D (struct maple_pnode *)((unsigned long)b.parent &
> > > +						  MA_ROOT_PARENT);
> > > +	} else {
> > > +		a.parent =3D (struct maple_pnode *)((unsigned long)a.parent &
> > > +						  MAPLE_NODE_MASK);
> > > +		b.parent =3D (struct maple_pnode *)((unsigned long)b.parent &
> > > +						  MAPLE_NODE_MASK);
> > > +	}
> > > +
> > > +	if (a.parent !=3D b.parent) {
> > > +		pr_err("The lower 8 bits of parents are different. %p %p\n",
> > > +			a.parent, b.parent);
> > > +		return -1;
> > > +	}
> > > +
> > > +	/*
> > > +	 * If it is a leaf node, the slots do not contain the node address,=
 and
> > > +	 * no special processing of slots is required.
> > > +	 */
> > > +	if (ma_is_leaf(type))
> > > +		goto cmp;
> > > +
> > > +	slots_a =3D ma_slots(&a, type);
> > > +	slots_b =3D ma_slots(&b, type);
> > > +
> > > +	for (i =3D 0; i < mt_slots[type]; i++) {
> > > +		if (!slots_a[i] && !slots_b[i])
> > > +			break;
> > > +
> > > +		if (!slots_a[i] || !slots_b[i]) {
> > > +			pr_err("The number of slots is different.\n");
> > > +			return -1;
> > > +		}
> > > +
> > > +		/* Do not compare addresses in slots. */
> > > +		((unsigned long *)slots_a)[i] &=3D MAPLE_NODE_MASK;
> > > +		((unsigned long *)slots_b)[i] &=3D MAPLE_NODE_MASK;
> > > +	}
> > > +
> > > +cmp:
> > > +	/*
> > > +	 * Compare all contents of two nodes, including parent (except addr=
ess),
> > > +	 * slots (except address), pivots, gaps and metadata.
> > > +	 */
> > > +	return memcmp(&a, &b, sizeof(struct maple_node));
> > > +}
> > > +
> > > +/*
> > > + * Compare two trees and return 0 if they are the same, non-zero oth=
erwise.
> > > + */
> > > +static int __init compare_tree(struct maple_tree *mt_a, struct maple=
_tree *mt_b)
> > > +{
> > > +	MA_STATE(mas_a, mt_a, 0, 0);
> > > +	MA_STATE(mas_b, mt_b, 0, 0);
> > > +
> > > +	if (mt_a->ma_flags !=3D mt_b->ma_flags) {
> > > +		pr_err("The flags of the two trees are different.\n");
> > > +		return -1;
> > > +	}
> > > +
> > > +	mas_dfs_preorder(&mas_a);
> > > +	mas_dfs_preorder(&mas_b);
> > > +
> > > +	if (mas_is_ptr(&mas_a) || mas_is_ptr(&mas_b)) {
> > > +		if (!(mas_is_ptr(&mas_a) && mas_is_ptr(&mas_b))) {
> > > +			pr_err("One is MAS_ROOT and the other is not.\n");
> > > +			return -1;
> > > +		}
> > > +		return 0;
> > > +	}
> > > +
> > > +	while (!mas_is_none(&mas_a) || !mas_is_none(&mas_b)) {
> > > +
> > > +		if (mas_is_none(&mas_a) || mas_is_none(&mas_b)) {
> > > +			pr_err("One is MAS_NONE and the other is not.\n");
> > > +			return -1;
> > > +		}
> > > +
> > > +		if (mas_a.min !=3D mas_b.min ||
> > > +		    mas_a.max !=3D mas_b.max) {
> > > +			pr_err("mas->min, mas->max do not match.\n");
> > > +			return -1;
> > > +		}
> > > +
> > > +		if (compare_node(mas_a.node, mas_b.node)) {
> > > +			pr_err("The contents of nodes %p and %p are different.\n",
> > > +			       mas_a.node, mas_b.node);
> > > +			mt_dump(mt_a, mt_dump_dec);
> > > +			mt_dump(mt_b, mt_dump_dec);
> > > +			return -1;
> > > +		}
> > > +
> > > +		mas_dfs_preorder(&mas_a);
> > > +		mas_dfs_preorder(&mas_b);
> > > +	}
> > > +
> > > +	return 0;
> > > +}
> > > +
> > > +static noinline void __init check_mt_dup(struct maple_tree *mt)
> > > +{
> > > +	DEFINE_MTREE(new);
> > > +	int i, j, ret, count =3D 0;
> > > +
> > > +	/* stored in the root pointer*/
> > > +	mt_init_flags(&tree, 0);
> > > +	mtree_store_range(&tree, 0, 0, xa_mk_value(0), GFP_KERNEL);
> > > +	mt_dup(&tree, &new, GFP_KERNEL);
> > > +	mt_validate(&new);
> > > +	if (compare_tree(&tree, &new))
> > > +		MT_BUG_ON(&new, 1);
> > > +
> > > +	mtree_destroy(&tree);
> > > +	mtree_destroy(&new);
> > > +
> > > +	for (i =3D 0; i < 1000; i +=3D 3) {
> > > +		if (i & 1)
> > > +			mt_init_flags(&tree, 0);
> > > +		else
> > > +			mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
> > > +
> > > +		for (j =3D 0; j < i; j++) {
> > > +			mtree_store_range(&tree, j * 10, j * 10 + 5,
> > > +					  xa_mk_value(j), GFP_KERNEL);
> > > +		}
> >=20
> > Storing in this way is probably not checking a full tree.  I think it's
> > important to check the full tree/full nodes since you have changes to
> > detect the metadata.
> I probably won't change the way I check metadata.

What I am tell you is that you haven't tested your new code for the
metadata of full nodes with this testcase, or have I missed something?
If it's not tested here, are there other testscases that cover the new
code?

>But is there a way to
> construct a full tree? All I can think of is to write new code to
> construct a full tree.

Normally, what I do, is create a tree in a loop like you have done above
and then store entries over a portion of existing ranges to fill out the
nodes until they are full.  check_ranges() in lib/test_maple_tree.c
might be of help.

> >=20
> > > +
> > > +		ret =3D mt_dup(&tree, &new, GFP_KERNEL);
> > > +		MT_BUG_ON(&new, ret !=3D 0);
> > > +		mt_validate(&new);
> > > +		if (compare_tree(&tree, &new))
> > > +			MT_BUG_ON(&new, 1);
> > > +
> > > +		mtree_destroy(&tree);
> > > +		mtree_destroy(&new);
> > > +	}
> > > +
> > > +	/* Test memory allocation failed. */
> > > +	for (i =3D 0; i < 1000; i +=3D 3) {
> > > +		if (i & 1)
> > > +			mt_init_flags(&tree, 0);
> > > +		else
> > > +			mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE);
> > > +
> > > +		for (j =3D 0; j < i; j++) {
> > > +			mtree_store_range(&tree, j * 10, j * 10 + 5,
> > > +					  xa_mk_value(j), GFP_KERNEL);
> > > +		}
> > > +
> > > +		mt_set_non_kernel(50);
> >=20
> > It may be worth while allowing more/less than 50 allocations.
> Actually I have used other values before. I haven't thought of a good
> value yet, probably a random number in a suitable range would be nice
> too.

random numbers are difficult to recreate so it might be best to limit
that to the userspace tools/testing/radix-tree/maple.c tests and print
the random number for reproducibility.

>=20
> >=20
> > > +		ret =3D mt_dup(&tree, &new, GFP_NOWAIT);
> > > +		mt_set_non_kernel(0);
> > > +		if (ret !=3D 0) {
> > > +			MT_BUG_ON(&new, ret !=3D -ENOMEM);
> > > +			count++;
> > > +			mtree_destroy(&tree);
> > > +			continue;
> > > +		}
> > > +
> > > +		mt_validate(&new);
> > > +		if (compare_tree(&tree, &new))
> > > +			MT_BUG_ON(&new, 1);
> > > +
> > > +		mtree_destroy(&tree);
> > > +		mtree_destroy(&new);
> > > +	}
> > > +
> > > +	/* pr_info("mt_dup() fail %d times\n", count); */
> > > +	BUG_ON(!count);
> > > +}
> > > +
> > >   extern void test_kmem_cache_bulk(void);
> > >   void farmer_tests(void)
> > > @@ -35904,6 +36102,10 @@ void farmer_tests(void)
> > >   	check_null_expand(&tree);
> > >   	mtree_destroy(&tree);
> > > +	mt_init_flags(&tree, 0);
> > > +	check_mt_dup(&tree);
> > > +	mtree_destroy(&tree);
> > > +
> > >   	/* RCU testing */
> > >   	mt_init_flags(&tree, 0);
> > >   	check_erase_testset(&tree);
> > > --=20
> > > 2.20.1
> > >=20
> > >=20