linux-kernel - Re: [PATCH RFC 1/2] rcutorture: Prevent concurrent kvm.sh runs on same source tree

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Message-ID: <3a6bfd87-570d-49fa-854f-8d5802549f6a@nvidia.com>
Date: Sun, 28 Dec 2025 17:37:33 -0500
From: Joel Fernandes <joelagnelf@...dia.com>
To: Randy Dunlap <rdunlap@...radead.org>,
 "Paul E . McKenney" <paulmck@...nel.org>,
 Josh Triplett <josh@...htriplett.org>, Steven Rostedt <rostedt@...dmis.org>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Lai Jiangshan <jiangshanlai@...il.com>, Shuah Khan <shuah@...nel.org>
Cc: rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH RFC 1/2] rcutorture: Prevent concurrent kvm.sh runs on
 same source tree



On 12/28/2025 5:34 PM, Randy Dunlap wrote:
> 
> 
> On 12/28/25 2:05 PM, Joel Fernandes wrote:
>> Add flock-based locking to kvm.sh to prevent multiple instances from
>> running concurrently on the same source tree. This prevents build
>> failures caused by one instance's "make clean" deleting generated files
>> while another instance is building causing build failures.
>>
>> The lock file is placed in the rcutorture directory and added to
>> .gitignore.
>>
>> Signed-off-by: Joel Fernandes <joelagnelf@...dia.com>
>> ---
>>  tools/testing/selftests/rcutorture/.gitignore |  1 +
>>  tools/testing/selftests/rcutorture/bin/kvm.sh | 17 +++++++++++++++++
>>  2 files changed, 18 insertions(+)
>>
>> diff --git a/tools/testing/selftests/rcutorture/.gitignore b/tools/testing/selftests/rcutorture/.gitignore
>> index f6cbce77460b..b8fd42547a6e 100644
>> --- a/tools/testing/selftests/rcutorture/.gitignore
>> +++ b/tools/testing/selftests/rcutorture/.gitignore
>> @@ -3,3 +3,4 @@ initrd
>>  b[0-9]*
>>  res
>>  *.swp
>> +.kvm.sh.lock
>> diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
>> index fff15821c44c..d1fbd092e22a 100755
>> --- a/tools/testing/selftests/rcutorture/bin/kvm.sh
>> +++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
>> @@ -275,6 +275,23 @@ do
>>  	shift
>>  done
>>  
>> +# Prevent concurrent kvm.sh runs on the same source tree.  The flock
>> +# is automatically released when the script exits, even if killed.
>> +TORTURE_LOCK="$RCUTORTURE/.kvm.sh.lock"
>> +if test -z "$dryrun"
>> +then
>> +	# Create a file descriptor and flock it, so that when kvm.sh (and its
>> +	# children) exit, the flock is released by the kernel automatically.
>> +	exec 9>"$TORTURE_LOCK"
>> +	if ! flock -n 9
>> +	then
>> +		echo "ERROR: Another kvm.sh instance is already running on this tree."
>> +		echo "       Lock file: $TORTURE_LOCK"
>> +		echo "       To run kvm.sh, kill all existing kvm.sh runs first."
>> +		exit 1
>> +	fi
>> +fi
>> +
>>  if test -n "$dryrun" || test -z "$TORTURE_INITRD" || tools/testing/selftests/rcutorture/bin/mkinitrd.sh
>>  then
>>  	:
>>
>> base-commit: 0ff41df1cb268fc69e703a08a57ee14ae967d0ca
>> prerequisite-patch-id: 912adecf969d167ddd35b26844249c809a2d4664
>> prerequisite-patch-id: 95ca224b0870cebb545ddaf313691fd18dfd04e1
>> prerequisite-patch-id: 68a218b9aaada53aa85cf33fcf4afe1592fe160f
>> prerequisite-patch-id: e40912ee9655a8abef17413a1bb9b05d2d4520de
>> prerequisite-patch-id: c0511755626728abcbed2f76e9a0b1d2f15e7c9e
>> prerequisite-patch-id: 0a8814cf3965ce3d5fb30d18db3daf2b96c3db74
>> prerequisite-patch-id: 450827b1f88e4ab714a63a24a66bd209f8c332af
> 
> Are all 54K of these required?

Ouch, this looks like a case of git format-patch scripting gone bad. Anyway, the
patches applies cleanly to Linus's master branch. I'll go look into the
scripting issue.

Thanks!

 - Joel