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[68.160.160.85]) by smtp.gmail.com with ESMTPSA id af79cd13be357-9377e616605sm295795885a.29.2026.08.26.13.26.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 26 Aug 2026 13:26:58 -0700 (PDT) Message-ID: Date: Wed, 26 Aug 2026 16:26:57 -0400 Precedence: bulk X-Mailing-List: live-patching@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 2/2] selftests/livepatch: filter debug messages in check_result() To: Petr Mladek , Yafang Shao Cc: jpoimboe@kernel.org, jikos@kernel.org, mbenes@suse.cz, song@kernel.org, live-patching@vger.kernel.org References: <20260821031648.48195-1-laoar.shao@gmail.com> <20260821031648.48195-3-laoar.shao@gmail.com> Content-Language: en-US From: Joe Lawrence Autocrypt: addr=joe.lawrence@redhat.com; keydata= xsFNBFgTlmsBEADfrZirrMsj9Z9umoJ5p1rgOitLBABITvPO2x5eGBRfXbT306zr226bhfPj +SDlaeIRwKoQvY9ydB3Exq8bKObYZ+6/OAVIDPHBVlnZbysutSHsgdaGqTH9fgYhoJlUIApz suQL0MIRkPi0y+gABbH472f2dUceGpEuudIcGvpnNVTYxqwbWqsSsfT1DaAz9iBCeN+T/f/J 5qOXyZT7lC6vLy07eGg0uBh9jQznhbfXPIev0losNe7HxvgaPaVQ+BS9Q8NF8qpvbgpO+vWQ ZD5+tRJ5t85InNiWR3bv01GcGXEjEVTnExYypajVuHxumqJeqGNeWvx26cfNRQJQxVQNV7Gz iyAmJO7UulyWQiJqHZPcXAfoWyeKKAJ37YIYfE3k+rm6ekIwSgc9Lacf+KBfESNooU1LnwoQ ok9Q6R5r7wqnhCziqXHfyN2YGhm0Wx4s7s6xIVrx3C5K0LjXBisjAthG/hbPhJvsCz5rTOmP jkr+GSwBy2XUdOmtgq1IheBFwvWf08vrzNRCqz3iI1CvRpz0ZYBazmkz924u4ul6W7JuCdgy qW3UDLA77XlzFrA7nJ6rb77aZF7LJlkahX7lMaKZUzH+K4aVKTdvZ3szm9K+v0iixsM0TEnz oWsZgrkAA0OX2lpLfXvskoujQ84lY989IF+nUwy0wRMJPeqNxwARAQABzSZKb2UgTGF3cmVu Y2UgPGpvZS5sYXdyZW5jZUByZWRoYXQuY29tPsLBlgQTAQgAQAIbAwcLCQgHAwIBBhUIAgkK CwQWAgMBAh4BAheAFiEEXzkJ3py1AClxRoHJx96nQticmuUFAmF2uf8FCRLJJRQACgkQx96n QticmuU69A/9FB5eF5kc392ifa/G6/m8q5BKVUXBMWy/RcRaEVUwl9lulJd99tkZT5KwwdIU eYSpmT4SXrMzHj3mWe8RcFT9S39RvmZA6UKQkt9mJ+dvUVyDW1pqAB+S6+AEJyzw9AoVPSIG WcHTCHdJZfZOMmFjDyduww7n94qXLO0oRMhjvR9vUqfBgEBSLzRSK96HI38brAcj33Q3lCkf 8uNLEAHVxN57bsNXxMYKo/i7ojFNCOyFEdPCWUMSF+M0D9ScXZRZCwbx0369yPSoNDgSIS8k iC/hbP2YMqaqYjxuoBzTTFuIS60glJu61RNealNjzvdlVz3RnNvD4yKz2JUsEsNGEGi4dRy7 tvULj0njbwdvxV/gRnKboWhXVmlvB1qSfimSNkkoCJHXCApOdW0Og5Wyi+Ia6Qym3h0hwG0r r+w8USCn4Mj5tBcRqJKITm92IbJ73RiJ76TVJksC0yEfbLd6x1u6ifNQh5Q7xMYk0t4VF6bR 56GG+3v1ci1bwwY5g1qfr7COU7in2ZOxhEpHtdt08MDSDFB3But4ko8zYqywP4sxxrJFzIdq 7Kv8a2FsLElJ3xG7jM260sWJfgZNI5fD0anbrzn9Pe1hShZY+4LXVJR/k3H01FkU9jWan0G/ 8vF04bVKng8ZUBBT/6OYoNQHzQ9z++h5ywgMTITy5EK+HhnOwU0EWBOWawEQALxzFFomZI1s 4i0a6ZUn4eQ6Eh2vBTZnMR2vmgGGPZNZdd1Ww62VnpZamDKFddMAQySNuBG1ApgjlFcpX0kV zm8PCi8XvUo0O7LHPKUkOpPM1NJKE1E3n5KqVbcTIftdTu3E/87lwBfEWBHIC+2K6K4GwSLX AMZvFnwqkdyxm9v0UiMSg87Xtf2kXYnqkR5duFudMrY1Wb56UU22mpZmPZ3IUzjV7YTC9Oul DYjkWI+2IN+NS8DXvLW8Dv4ursCiP7TywkxaslVT8z1kqtTUFPjH10aThjsXB5y/uISlj7av EJEmj2Cbt14ps6YOdCT8QOzXcrrBbH2YtKp2PwA3G3hyEsCFdyal8/9h0IBgvRFNilcCxxzq 3gVtrYljN1IcXmx87fbkV8uqNuk+FxR/dK1zgjsGPtuWg1Dj/TrcLst7S+5VdEq87MXahQAE O5qqPjsh3oqW2LtqfXGSQwp7+HRQxRyNdZBTOvhG0sys4GLlyKkqAR+5c6K3Qxh3YGuA77Qb 1vGLwQPfGaUo3soUWVWRfBw8Ugn1ffFbZQnhAs2jwQy3CILhSkBgLSWtNEn80BL/PMAzsh27 msvNMMwVj/M1R9qdk+PcuEJXvjqQA4x/F9ly/eLeiIvspILXQ5LodsITI1lBN2hQSbFFYECy a4KuPkYHPZ3uhcfB0+KroLRxABEBAAHCwXwEGAEIACYCGwwWIQRfOQnenLUAKXFGgcnH3qdC 2Jya5QUCYXa52AUJEskk7QAKCRDH3qdC2Jya5awND/9d9YntR015FVdn910u++9v64fchT+m LqD+WL24hTUMOKUzAVxq+3MLN4XRIcig4vnLmZ2sZ7VXstsukBCNGdm8y7Y8V1tXqeor82IY aPzfFhcTtMWOvrb3/CbwxHWM0VRHWEjR7UXG0tKt2Sen0e9CviScU/mbPHAYsQDkkbkNFmaV KJjtiVlTaIwq/agLZUOTzvcdTYD5QujvfnrcqSaBdSn1+LH3af5T7lANU6L6kYMBKO+40vvk r5w5pyr1AmFU0LCckT2sNeXQwZ7jR8k/7n0OkK3/bNQMlLx3lukVZ1fjKrB79b6CJUpvTUfg 9uxxRFUmO+cWAjd9vOHT1Y9pgTIAELucjmlmoiMSGpbhdE8HNesdtuTEgZotpT1Q2qY7KV5y 46tK1tjphUw8Ln5dEJpNv6wFYFKpnKsiiHgWAaOuWkpHWScKfNHwdbXOw7kvIOrHV0euKhFa 0j0S2Arb+WjjMSJQ7WpC9rzkq1kcpUtdWnKUC24WyZdZ1ZUX2dW2AAmTI1hFtHw42skGRCXO zOpdA5nOdOrGzIu0D9IQD4+npnpSIL5IW9pwZMkkgoD47pdeekzG/xmnvU7CF6iDBzwuG3CC FPtyZxmwRVoS/YeBgzoyEDTwUJDzNGrkkNKnaUbDpg4TLRSCUUhmDUguj0QCa4n8kYoaAw9S pNzsRQ== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/26/26 3:54 AM, Petr Mladek wrote: > On Fri 2026-08-21 11:16:48, Yafang Shao wrote: >> CONFIG_DEBUG_KOBJECT makes kobject_add_internal(), kobject_uevent_env(), >> fill_kobj_path() and friends emit pr_debug() messages, and >> CONFIG_DEBUG_KOBJECT_RELEASE makes kobject_release() emit a pr_info() >> for every delayed kobject free. All of these carry the "kobject:" prefix >> via pr_fmt(), e.g.: >> >> # --- expected >> # +++ result >> # @@ -1,7 +1,13 @@ >> # % insmod test_modules/test_klp_livepatch.ko >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_add_internal: parent: 'module', set: 'module' >> # +kobject: 'holders' (000000002856f0ae): kobject_add_internal: parent: 'test_klp_livepatch', set: '' >> # +kobject: 'test_klp_livepatch' (00000000dcae1113): kobject_add_internal: parent: 'livepatch', set: '' >> # +kobject: 'vmlinux' (000000007b8837e6): kobject_add_internal: parent: 'test_klp_livepatch', set: '' >> # livepatch: enabling patch 'test_klp_livepatch' >> # livepatch: 'test_klp_livepatch': initializing patching transition >> # livepatch: 'test_klp_livepatch': starting patching transition >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_uevent_env >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): fill_kobj_path: path = '/module/test_klp_livepatch' >> # livepatch: 'test_klp_livepatch': completing patching transition >> # livepatch: 'test_klp_livepatch': patching complete >> # % echo 0 > /sys/kernel/livepatch/test_klp_livepatch/enabled >> # @@ -9,4 +15,17 @@ livepatch: 'test_klp_livepatch': initial >> # livepatch: 'test_klp_livepatch': starting unpatching transition >> # livepatch: 'test_klp_livepatch': completing unpatching transition >> # livepatch: 'test_klp_livepatch': unpatching complete >> # +kobject: 'test_klp_livepatch' (00000000dcae1113): kobject_release, parent 00000000f8785d63 (delayed 2000) >> # +kobject: 'test_klp_livepatch' (00000000dcae1113): kobject_cleanup, parent 00000000f8785d63 >> # +kobject: 'test_klp_livepatch' (00000000dcae1113): auto cleanup kobject_del >> # +kobject: 'test_klp_livepatch' (00000000dcae1113): calling ktype release >> # +kobject: 'test_klp_livepatch': free name >> # % rmmod test_klp_livepatch >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_release, parent 0000000052e5c022 (delayed 3000) >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_cleanup, parent 0000000052e5c022 >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): auto cleanup kobject_del >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): auto cleanup 'remove' event >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): kobject_uevent_env >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): fill_kobj_path: path = '/module/test_klp_livepatch' >> # +kobject: 'test_klp_livepatch' (000000009dbf565e): calling ktype release >> # +kobject: 'test_klp_livepatch': free name >> # >> # ERROR: livepatch kselftest(s) failed >> not ok 1 selftests: livepatch: test-livepatch.sh # exit=1 >> >> The livepatch test modules' kobjects are named "test_klp_*", so these >> lines match the check_result() grep for "test_klp" and leak into the >> result. The extra lines no longer match the expected output, so the >> selftests fail when either debug config is enabled. >> >> Filtering out every "kobject:" line also hides real WARN()s, e.g. the >> one kobject_get() emits for an object whose refcount was not >> initialized. Filtering with "dmesg --level=..." is not enough either, >> since the tests enable livepatch pr_debug() through dynamic_debug/control >> and expect its messages. Read the log with "dmesg --raw" and drop only >> the debug-level messages without the "livepatch:" prefix, plus the >> specific delayed-release info message. >> >> Suggested-by: Petr Mladek >> Signed-off-by: Yafang Shao > > I am not much familiar with awk. But the changes look good > and selftests passed so: > I translate the awk as: - read through the steam, print nothing yet, - when the last_dmesg line is encountered, set the p variable - continue through the stream and if p is set, - print a line if its initial field is "<7>" or "livepatch:" which LGTM. One dmesg nit: years ago someone complained about BusyBox vs. selftests compatibility: https://lore.kernel.org/live-patching/20200710183745.19730-1-joe.lawrence@redhat.com/ and my google-foo tells me that its dmesg only supports -r and not --raw. I don't know if it's worth using the short option without testing it, but -r would also supported by util-linux's dmesg, fwiw. -- Joe