From: Qian Cai <cai@lca.pw>
To: Matthew Wilcox <willy@infradead.org>
Cc: akpm@linux-foundation.org, esploit@protonmail.ch,
jejb@linux.ibm.com, dgilbert@interlog.com,
martin.petersen@oracle.com, joeypabalinas@gmail.com,
walken@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] rbtree: fix the red root
Date: Fri, 11 Jan 2019 19:18:55 -0500 [thread overview]
Message-ID: <463fa1f6-4ee6-ef4d-431c-3c392c827792@lca.pw> (raw)
In-Reply-To: <20190111231652.GN6310@bombadil.infradead.org>
On 1/11/19 6:16 PM, Matthew Wilcox wrote:
> On Fri, Jan 11, 2019 at 03:58:43PM -0500, Qian Cai wrote:
>> diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c
>> index b7055b2a07d3..afad0213a117 100644
>> --- a/lib/rbtree_test.c
>> +++ b/lib/rbtree_test.c
>> @@ -345,6 +345,17 @@ static int __init rbtree_test_init(void)
>> check(0);
>> }
>>
>> + /*
>> + * a little regression test to catch a bug may be introduced by
>> + * 6d58452dc06 (rbtree: adjust root color in rb_insert_color() only when
>> + * necessary)
>> + */
>> + insert(nodes, &root);
>> + nodes->rb.__rb_parent_color = RB_RED;
>> + insert(nodes + 1, &root);
>> + erase(nodes + 1, &root);
>> + erase(nodes, &root);
>
> That's not a fair test! You're poking around in the data structure to
> create the situation. This test would have failed before 6d58452dc06 too.
> How do we create a tree that has a red parent at root, only using insert()
> and erase()?
>
If only I knew how to reproduce this myself, I might be able to figure out how
it ends up with the red root in the first place.
next prev parent reply other threads:[~2019-01-12 0:18 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <YrcPMrGmYbPe_xgNEV6Q0jqc5XuPYmL2AFSyeNmg1gW531bgZnBGfEUK5_ktqDBaNW37b-NP2VXvlliM7_PsBRhSfB649MaW1Ne7zT9lHc=@protonmail.ch>
2019-01-11 16:51 ` [PATCH] " Qian Cai
2019-01-11 17:17 ` Joey Pabalinas
2019-01-11 17:31 ` Matthew Wilcox
2019-01-11 17:53 ` Joey Pabalinas
2019-01-11 18:12 ` Qian Cai
2019-01-11 18:12 ` Qian Cai
2019-01-11 18:16 ` Matthew Wilcox
2019-01-11 18:16 ` Matthew Wilcox
2019-01-11 20:58 ` [PATCH v2] " Qian Cai
2019-01-11 23:16 ` Matthew Wilcox
2019-01-12 0:18 ` Qian Cai [this message]
2019-01-12 0:39 ` Esme
2019-01-11 23:47 ` David Lechner
2019-01-12 2:58 ` Michel Lespinasse
2019-01-12 2:58 ` Michel Lespinasse
2019-01-14 2:20 ` David Lechner
2019-01-14 2:33 ` Qian Cai
2019-01-14 3:07 ` Esme
2019-01-14 3:52 ` Douglas Gilbert
2019-01-14 3:59 ` Esme
2019-01-14 4:52 ` Douglas Gilbert
2019-01-14 6:23 ` Esme
2019-01-14 15:45 ` Qian Cai
2019-01-14 15:51 ` Esme
2019-01-14 17:58 ` Qian Cai
2019-01-14 18:26 ` Douglas Gilbert
2019-01-15 5:31 ` Qian Cai
2019-01-16 14:37 ` Esme
2019-01-18 17:10 ` Qian Cai
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