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From: Matthew Wilcox <willy@infradead.org>
To: Qian Cai <cai@lca.pw>
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 15:16:52 -0800
Message-ID: <20190111231652.GN6310@bombadil.infradead.org> (raw)
In-Reply-To: <20190111205843.25761-1-cai@lca.pw>

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()?

  reply index

Thread overview: 26+ 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 18:16       ` Matthew Wilcox
2019-01-11 20:58         ` [PATCH v2] " Qian Cai
2019-01-11 23:16           ` Matthew Wilcox [this message]
2019-01-12  0:18             ` Qian Cai
2019-01-12  0:39               ` Esme
2019-01-11 23:47           ` David Lechner
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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