linux-kernel - [RFC] hung_task: task white-listing for hung tasks

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Message-ID: <9a25d3183d2e4c99aa942d6beeb151f4@bgmail102.nvidia.com>
Date:	Thu, 12 May 2016 08:51:58 +0000
From:	Aniruddha Banerjee <aniruddhab@...dia.com>
To:	"levinsasha928@...il.com" <levinsasha928@...il.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"msb@...gle.com" <msb@...gle.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [RFC] hung_task: task white-listing for hung tasks

Hello,

In the current hung_task framework, there is no way to white-list tasks for which a higher hang time out might be acceptable and expected even:

Usecase: I want to keep a low hung_task timeout to catch more tasks which are hung-up. However, certain tasks (like sync, which flushes to a slow eMMC) may have a higher timeout.

Problem: There is no way to implement the aforementioned usecase without increasing the hang task timeout, which will reduce the effictiveness of the hung_task framework.

Solution:

1. Introduce a white-list of tasks that have a much higher timeout.
2. Create a simple sysfs interface with which it might be possible to dynamically add/remove any task in the white-list.

Please let me know what you think about the problem and the proposed solution?

Regards,
Aniruddha