linux-kernel - Re: [PATCH 2/2] maple_tree: Add some alloc node test case

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Message-ID: <20241015133125.aixhbw5kunbme2nt@master>
Date: Tue, 15 Oct 2024 13:31:25 +0000
From: Wei Yang <richard.weiyang@...il.com>
To: "Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Wei Yang <richard.weiyang@...il.com>, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiazi Li <jqqlijiazi@...il.com>, linux-kernel@...r.kernel.org,
	maple-tree@...ts.infradead.org
Subject: Re: [PATCH 2/2] maple_tree: Add some alloc node test case

On Mon, Oct 14, 2024 at 09:15:07PM -0400, Liam R. Howlett wrote:
>* Wei Yang <richard.weiyang@...il.com> [241010 21:18]:
>> On Wed, Jun 26, 2024 at 12:06:31PM -0400, Liam R. Howlett wrote:
>> >From: Jiazi Li <jqqlijiazi@...il.com>
>> >
>> >Add some maple_tree alloc node tese case.
>> >
>> >Suggested-by: Liam R. Howlett <Liam.Howlett@...cle.com>
>> >Signed-off-by: Jiazi Li <jqqlijiazi@...il.com>
>> >Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
>> >---
>> > tools/testing/radix-tree/maple.c | 22 ++++++++++++++++++++++
>> > 1 file changed, 22 insertions(+)
>> >
>> >diff --git a/tools/testing/radix-tree/maple.c b/tools/testing/radix-tree/maple.c
>> >index 11f1efdf83f9..b4b5fd9f294d 100644
>> >--- a/tools/testing/radix-tree/maple.c
>> >+++ b/tools/testing/radix-tree/maple.c
>> >@@ -462,6 +462,28 @@ static noinline void __init check_new_node(struct maple_tree *mt)
>> > 	MT_BUG_ON(mt, mas_allocated(&mas) != 10 + MAPLE_ALLOC_SLOTS - 1);
>> > 	mas_destroy(&mas);
>> > 
>> >+	mas.node = MA_ERROR(-ENOMEM);
>> >+	mas_node_count(&mas, MAPLE_ALLOC_SLOTS + 1); /* Request */
>> >+	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
>> 
>> I am not sure why mas_nomem() is here.
>> 
>> Without this one, we still can trigger the original bug.
>
>It will fill the maple state allocation.  Might not be needed but
>doesn't hurt.
>

I took another look at it. We really need mas_nomem() here, since we call
mt_set_non_kernel(0) at the beginning of check_new_node(). 

So mas_node_count() just set the request count and mas_nomem() does the real
allocation.

Any reason to design test case like this?

>> 
>> >+	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS + 1);
>> >+	mas.node = MA_ERROR(-ENOMEM);
>> >+	mas_node_count(&mas, MAPLE_ALLOC_SLOTS * 2 + 2); /* Request */
>> >+	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
>> >+	mas.status = ma_start;
>> >+	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS * 2 + 2);
>> >+	mas_destroy(&mas);
>> >+
>> >+	mas.node = MA_ERROR(-ENOMEM);
>> >+	mas_node_count(&mas, MAPLE_ALLOC_SLOTS * 2 + 1); /* Request */
>> >+	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
>> >+	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS * 2 + 1);
>> >+	mas.node = MA_ERROR(-ENOMEM);
>> >+	mas_node_count(&mas, MAPLE_ALLOC_SLOTS * 3 + 2); /* Request */
>> >+	mas_nomem(&mas, GFP_KERNEL); /* Fill request */
>> >+	mas.status = ma_start;
>> >+	MT_BUG_ON(mt, mas_allocated(&mas) != MAPLE_ALLOC_SLOTS * 3 + 2);
>> >+	mas_destroy(&mas);
>> >+
>> > 	mtree_unlock(mt);
>> > }
>> > 
>> >-- 
>> >2.43.0
>> >
>> 
>> -- 
>> Wei Yang
>> Help you, Help me

-- 
Wei Yang
Help you, Help me