linux-kernel - Re: [PATCH v2 05/12] rcutorture: Add tests for SRCU up/down reader primitives

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Message-ID: <553c33d8-2b51-4772-8aef-97b0163bc78e@nvidia.com>
Date: Tue, 15 Apr 2025 21:14:36 -0400
From: Joel Fernandes <joelagnelf@...dia.com>
To: paulmck@...nel.org
Cc: rcu@...r.kernel.org, linux-kernel@...r.kernel.org, kernel-team@...a.com,
 rostedt@...dmis.org
Subject: Re: [PATCH v2 05/12] rcutorture: Add tests for SRCU up/down reader
 primitives



On 4/15/2025 5:15 PM, Paul E. McKenney wrote:
> On Tue, Apr 15, 2025 at 10:59:36AM -0700, Paul E. McKenney wrote:
>> On Tue, Apr 15, 2025 at 01:16:15PM -0400, Joel Fernandes wrote:
>>>
>>>
>>> On 3/31/2025 5:03 PM, Paul E. McKenney wrote:
>>>> This commit adds a new rcutorture.n_up_down kernel boot parameter
>>>> that specifies the number of outstanding SRCU up/down readers, which
>>>> begin in kthread context and end in an hrtimer handler.  There is a new
>>>> kthread ("rcu_torture_updown") that scans an per-reader array looking
>>>> for elements whose readers have ended.  This kthread sleeps between one
>>>> and two milliseconds between consecutive scans.
>>>>
>>>> [ paulmck: Apply kernel test robot feedback. ]
>>>> [ paulmck: Apply Z qiang feedback. ]
>>>>
>>>> Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
>>>
>>> For completeness, posting our discussion for the archives, an issue exists in
>>> this patch causing the following errors on an ARM64 machine with 288 CPUs:
>>>
>>> When running SRCU-P test, we intermittently see:
>>>
>>> [ 9500.806108] ??? Writer stall state RTWS_SYNC(21) g18446744073709551218 f0x0
>>> ->state 0x2 cpu 4
>>> [ 9515.833356] ??? Writer stall state RTWS_SYNC(21) g18446744073709551218 f0x0
>>> ->state 0x2 cpu 4
>>>
>>> It bisected to just this patch.
>>
>> Looks like your getting rcutorture running on ARM was well timed!

Yes! Glad I could help.

> 
> And could you please send along your dmesg and .config files?
> 

Sure, attached both for one of the failed runs.

 - Joel


View attachment "config.txt" of type "text/plain" (308924 bytes)

View attachment "console.log" of type "text/plain" (66279 bytes)