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Date:   Wed, 24 Feb 2021 09:44:14 -0500
From:   "J. Bruce Fields" <bfields@fieldses.org>
To:     Luo Longjun <luolongjun@huawei.com>
Cc:     viro@zeniv.linux.org.uk, jlayton@kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        sangyan@huawei.com, luchunhua@huawei.com
Subject: Re: [PATCH v2 02/24] fs/locks: print full locks information
Message-ID: <20210224144414.GA11591@fieldses.org>
References: <YDKP0XdT1TVOaGnj@zeniv-ca.linux.org.uk>
 <20210224083544.750887-1-luolongjun@huawei.com>
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On Wed, Feb 24, 2021 at 03:35:44AM -0500, Luo Longjun wrote:
> @@ -2912,17 +2922,66 @@ static int locks_show(struct seq_file *f, void *v)
>  	struct file_lock *fl, *bfl;
>  	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
>  
> +	struct list_head root;
> +	struct list_head *tail = &root;
> +	struct list_head *pos, *tmp;
> +	struct locks_traverse_list *node, *node_child;
> +
> +	int ret = 0;
> +
>  	fl = hlist_entry(v, struct file_lock, fl_link);
>  
>  	if (locks_translate_pid(fl, proc_pidns) == 0)
> -		return 0;
> +		return ret;
> +
> +	INIT_LIST_HEAD(&root);
>  
> -	lock_get_status(f, fl, iter->li_pos, "");
> +	node = kmalloc(sizeof(struct locks_traverse_list), GFP_KERNEL);

Is it safe to allocate here?  I thought this was under the
blocked_lock_lock spinlock.

And I still don't think you need a stack.  Have you tried the suggestion
in my previous mail?

--b.