linux-kernel - [PATCH 0/2] hung_task: Provide runtime reset interface for hung task detector

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Message-ID: <20251209041218.1583600-1-atomlin@atomlin.com>
Date: Mon,  8 Dec 2025 23:12:16 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: akpm@...ux-foundation.org,
	lance.yang@...ux.dev,
	mhiramat@...nel.org,
	gregkh@...uxfoundation.org
Cc: sean@...e.io,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] hung_task: Provide runtime reset interface for hung task detector

Introduce a write-only sysfs attribute,
/sys/kernel/hung_task_detect_count_reset, to reset the total count of
detected hung tasks at runtime.

The attribute requires writing the value "1" to trigger the reset and returns
-EINVAL for any other input, ensuring robustness.

This addition is primarily justified by the need for enhanced
administrative control and improved diagnostics workflow in a running
production environment. It addresses a key limitation of the existing
mechanism: the inability to clear persistent state without resorting to a
full system reboot. The sysfs interface provides a non-disruptive, runtime
method to manage the diagnostic state.

After a system administrator investigates a potential hang and corrects the issue,
it is now possible to clear the history back to zero. This provides a clean
slate for subsequent monitoring, ensuring that any new recurrence of a hung
task is immediately reflected by a counter value greater than zero,
streamlining the post-mortem diagnostic phase.

Aaron Tomlin (2):
  hung_task: Consolidate hung task warning into an atomic log block
  hung_task: Provide runtime reset interface for hung task detector

 .../sysfs-kernel-hung_task_detect_count_reset |  8 +++
 kernel/hung_task.c                            | 68 ++++++++++++++++---
 2 files changed, 66 insertions(+), 10 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-kernel-hung_task_detect_count_reset

-- 
2.51.0