From: Lance Yang <lance.yang@linux.dev>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Waiman Long <longman@redhat.com>,
Joel Granados <joel.granados@kernel.org>,
Anna Schumaker <anna.schumaker@oracle.com>,
Lance Yang <ioworker0@gmail.com>,
Kent Overstreet <kent.overstreet@linux.dev>,
Yongliang Gao <leonylgao@tencent.com>,
Steven Rostedt <rostedt@goodmis.org>,
Tomasz Figa <tfiga@chromium.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] hung_task: Dump blocker task if it is not hung
Date: Thu, 31 Jul 2025 12:45:17 +0800 [thread overview]
Message-ID: <d63b51f2-7c63-49ff-8dfe-f92a60db7c19@linux.dev> (raw)
In-Reply-To: <l27knfwpljnsgwvc47ifxtrwtuwaireojejiozjioqab5va65l@vrkuak2n3hll>
On 2025/7/31 11:37, Sergey Senozhatsky wrote:
> On (25/07/31 11:25), Lance Yang wrote:
>>>> Wrote a simple 3 tasks circular lock test (same that I had in real
>>>> life). The output looks good:
>>>
>>> Nice work! The log is now much clearer ;)
>>
>> Forgot to add:
>>
>> This circular lock test is great. It would be very valuable to have
>> it in samples/hung_task ;)
>>
>> Would you be willing to submit it as a patch?
>
> Well, that particular test is a deadlock, not sure how useful a test
> that deadlocks is going to be. We probably need some alternative if
> we want to test backtrace de-dup.
Yep, you're right. A permanent deadlock is a no-go for a reusable test.
Maybe we need a test like a blocker chain (T1->T2->T3), where T3 holds
the lock and just sleeps for a while. Once it wakes up and releases the
lock, everything can finish cleanly.
Also, I might try to cook up a sample for that, time permitting ;)
next prev parent reply other threads:[~2025-07-31 4:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-30 22:11 [PATCH v2] hung_task: Dump blocker task if it is not hung Masami Hiramatsu (Google)
2025-07-31 2:53 ` Sergey Senozhatsky
2025-07-31 3:15 ` Lance Yang
2025-07-31 3:25 ` Lance Yang
2025-07-31 3:37 ` Sergey Senozhatsky
2025-07-31 4:45 ` Lance Yang [this message]
2025-07-31 5:58 ` Masami Hiramatsu
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