linux-kernel - Re: [PATCH] hung_task: Increment the global counter immediately

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Message-ID: <74f33626-85c5-4bed-866d-1be20ecb09a5@linux.dev>
Date: Sat, 7 Feb 2026 14:10:35 +0800
From: Lance Yang <lance.yang@...ux.dev>
To: Aaron Tomlin <atomlin@...mlin.com>
Cc: Petr Mladek <pmladek@...e.com>, neelx@...e.com, sean@...e.io,
 mproche@...il.com, chjohnst@...il.com, nick.lange@...il.com,
 linux-kernel@...r.kernel.org, mhiramat@...nel.org, joel.granados@...nel.org,
 gregkh@...uxfoundation.org, Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] hung_task: Increment the global counter immediately



On 2026/2/7 04:54, Aaron Tomlin wrote:
> On Wed, Feb 04, 2026 at 10:05:49AM -0800, Andrew Morton wrote:
>> On Wed, 4 Feb 2026 12:04:54 +0100 Petr Mladek <pmladek@...e.com> wrote:
>>
>>> A recent change allowed to reset the global counter of hung tasks using
>>> the sysctl interface. A potential race with the regular check has been
>>> solved by updating the global counter only once at the end of the check.
>>>
>>> However, the hung task check can take a significant amount of time,
>>> particularly when task information is being dumped to slow serial
>>> consoles. Some users monitor this global counter to trigger immediate
>>> migration of critical containers. Delaying the increment until the
>>> full check completes postpones these high-priority rescue operations.
>>>
>>> Update the global counter as soon as a hung task is detected. Since
>>> the value is read asynchronously, a relaxed atomic operation is
>>> sufficient.
>>>
>>> Reported-by: Lance Yang <lance.yang@...ux.dev>
>>> Closes: https://lore.kernel.org/r/f239e00f-4282-408d-b172-0f9885f4b01b@linux.dev
>>> Signed-off-by: Petr Mladek <pmladek@...e.com>
>>> ---
>>> This is a followup patch for
>>> https://lore.kernel.org/r/20260125135848.3356585-1-atomlin@atomlin.com
>>>
>>> Note that I could not use commit IDs because the original
>>> patchset is not in a stable tree yet. In fact, it seems
>>> that it is not even in linux-next at the moment.
>>
>> Yes, I've gone into "fixes and trivial stuff only" mode, as we're at -rc8.
>>
>> Aaron, please incorporate Petr's fix into v8 and resend towards the end
>> of the merge window?
>>
>> Thanks.
> 
> Hi Andrew,
> 
> Absolutely.

Don't forget to credit Petr - just saying :)