From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f66.google.com (mail-ej1-f66.google.com [209.85.218.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 89390265CDD for ; Thu, 11 Sep 2025 15:55:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.66 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757606153; cv=none; b=eQQZg64gp2HpKaMsH16qrAiREYX01V4//vcKdFWBwQl1minFTDbOxO2B1SMBnAoYT7kRNRHABwWga7D2xpudpoAc17doj6Qx2SBUtXPeFFWLzaGui6iePuxJxQHODNNZ/o4LmyZ2ug5POTd6eqBiTaRgrDN80Yisw43gvbVU4UM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757606153; c=relaxed/simple; bh=5caI5z6boVJD8o3Qn0pwQ0J6yngyS4IHgtF1g+nxoWs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Org7m0SwaKSMzjBZY0a1nVU6hMFU7GCcqbRQQtX/xpMTm+ZgyGzr9XEy7ZNAL2nRrhGUNScUd+kCKtpYbhFUA+Exd+rtPMPMz98rZ0lgH+WVv5rQxZ4BpSNmYOE1llfYIfids5Nd4SWgyIKqkSLXmUpPvgNjhDpABsPenACGAAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=J6XATnQ0; arc=none smtp.client-ip=209.85.218.66 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="J6XATnQ0" Received: by mail-ej1-f66.google.com with SMTP id a640c23a62f3a-b04b55d5a2cso155397166b.2 for ; Thu, 11 Sep 2025 08:55:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1757606149; x=1758210949; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=aZ1xH/n+WEalzMjvlkdL2OhZWHiUBYRYpTYaB69REYQ=; b=J6XATnQ0RKVvBvO+WkzxoNe7uqsEQioQjL0b+V0gBzUulDhoTilgz4N9ODfPItsdcf r6XN13pyGyPCY+OnSEhTxAiLLKrCq/IZ5aqLr2bmyiZLWaSP6uYwnJnIdo0wgXjlUpgj n8qej3pvwGrQCtRCpxXj6QCN0AFh//I8Ux4Q4S/rzcVO8SoriCdpKENVQj9CfSy1ybjN aU+R1m0tpTXPfWmdwg0Dz90ayu472RB/5t9PII53/jvuq1IoN3aipbT2iLB9Z1fMrFCa wzIjtdqfClIrnhFICR1hgDyBSRHx3TGoF2u4TEQU1niGeDz+j2dBdMQjJUA4dAf2GLls wRPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757606149; x=1758210949; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=aZ1xH/n+WEalzMjvlkdL2OhZWHiUBYRYpTYaB69REYQ=; b=JfNa/MFkHiCCyJDVJ8ErTwlS3sSKmUoWPhfK6DXhI0dDSlklA2ttaR97G30qzUb8Wb p20YwKcOfi31bQAy+Dn8Hp+AOdrPY01/kxkYX+GAVr9OIq39iFriPFgirdU60VfTWnin MU++PRuhCuIcFJlEtCXGcGVmz4kXkiwJSElZwqkhXA8foJUK92s4FGasuqq/N84rX4QV bV+EqV2+kKRTsG0Eqd0p2GTX1dmLc657bpdifH11xoMJsMckP81TAkKzLA3XSr+Rlk0L dNcY+/d9ll5CWaNpxNjhgPwCqeYPytqAOc8BBXVpjOGi/Mi8ZuEdg0IrptSbfDJT83v7 mTDA== X-Gm-Message-State: AOJu0Yz9+RQFynBQ2mLsewczmHxo3eMtC4b7DoH1fWQZ9ygdcWZ8wjTi jJH5n21FWvmy/mnXMygdtzxc8BzQ4z/5ZPigcn2oOleopMXQcWAxROB+qMtVtvKzujw= X-Gm-Gg: ASbGnctRqlbNZIrrN6MUkj3hUBfe1RtnddQFg2FNu6Og62k04L53yE8Q5SJu21WneWz im776JMWRzie4CWjRuVVTM7rzI64xGc4qVukBq/jfWIOugpzbl2/EtpDMNWOvxxx5OgHt//ELjM zJCIYMnNlwWIwhe2R4Bc9pw5bJkcoMKSyu9xxjdp4gIeKF1JF8869tnm+DlTQ4cUzhpfG1OPMGM nVUi6Mlc0tgydaOE8QAA19oSKGFP2tnpNsoN8tPiSeod3Vo54aJtJmUPsv4KiwmGzSROn9zfzVY QbH/yrm4NPThyBGDPgvweiQ3NyZiLkgcW79N8kHGBvzkgSSHAxU96pRqwBvhdRaKF09FDcqC5Gf wo6Pg6RnyUHI4NqSy4ZqGf+zoa9cvqfOqd7P8 X-Google-Smtp-Source: AGHT+IEQayCLlY4P9qt+koJf+eZXhLP1kss8EF5cNM+0QRAXJcyOYBHXk44saPdnU8CKSRcia5aXKg== X-Received: by 2002:a17:907:d16:b0:b04:568b:8a42 with SMTP id a640c23a62f3a-b04b14bbbf0mr1983586366b.29.1757606148685; Thu, 11 Sep 2025 08:55:48 -0700 (PDT) Received: from pathway.suse.cz ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b07b32f22b1sm162094266b.86.2025.09.11.08.55.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Sep 2025 08:55:48 -0700 (PDT) Date: Thu, 11 Sep 2025 17:55:46 +0200 From: Petr Mladek To: Daniil Tatianin Cc: linux-kernel@vger.kernel.org, Steven Rostedt , John Ogness , Sergey Senozhatsky Subject: Re: [PATCH v2 0/2] printk_ringbuffer: don't needlessly wrap data blocks around Message-ID: References: <20250905144152.9137-1-d-tatianin@yandex-team.ru> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Thu 2025-09-11 17:30:36, Petr Mladek wrote: > On Fri 2025-09-05 17:41:50, Daniil Tatianin wrote: > > This series fixes the issue where data blocks would wrap in cases where the last > > data block perfectly fits the ring. This caused whatever was at the beginning of > > the ring to get discarded in this case, and the data block would get put there > > even though it could be put at the end of the data ring just fine without > > discarding anything. > > > > Fixing this issue also allows to simplify the check in data_check_size, > > previously it would ensure there's space for a trailing id, which we > > don't need anymore. > > > > v0->v1: > > - Fix severely broken code alignment > > > > v1->v2: > > - Rename & invert get_next_lpos -> is_blk_wrapped > > - Add a new commit for changing the logic in data_check_size > > The patchset looks good to me. But I wanted to do some tests > and it failed. I did the following: > > 1. Applied this patchset on top of printk/linux.git, branch for-next, > https://git.kernel.org/pub/scm/linux/kernel/git/printk/linux.git/log/?h=for-next > > I this branch because it contains a new KUnit test for the printk > ring buffer. The KUnit test fails even without this patchset, see below. > 2. I applied the following patch: > > + It reduces the size of the data ring. If I count it correctly > it should be 256 (2 << 8). > > + It increases the maximal size of the text so that the maximal > record size is 256. > > 3. I built it with Kasan enabled: > > $> grep KASAN .config > CONFIG_KASAN_SHADOW_OFFSET=0xdffffc0000000000 > CONFIG_HAVE_ARCH_KASAN=y > CONFIG_HAVE_ARCH_KASAN_VMALLOC=y > CONFIG_CC_HAS_KASAN_GENERIC=y > CONFIG_CC_HAS_KASAN_SW_TAGS=y > CONFIG_KASAN=y > CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX=y > CONFIG_KASAN_GENERIC=y > # CONFIG_KASAN_OUTLINE is not set > CONFIG_KASAN_INLINE=y > CONFIG_KASAN_STACK=y > CONFIG_KASAN_VMALLOC=y > # CONFIG_KASAN_KUNIT_TEST is not set > # CONFIG_KASAN_EXTRA_INFO is not set > > > 4. I loaded the test module: > > # depmod > # modprobe printk_ringbuffer_kunit_test > > I am not sure if it is caused by this patchset or Hmm, the KUnit test fails even after reverting this patchset. I havn't hit the WARN_ON_ONCE() in get_data() yet. But the data seem to be corrupted. This is from two runs: [ 45.808363] printk_ringbuffer_kunit_test: module verification failed: signature and/or required key missing - tainting kernel [ 45.820389] KTAP version 1 [ 45.820682] 1..1 [ 45.822088] KTAP version 1 [ 45.822387] # Subtest: printk-ringbuffer [ 45.822729] # module: printk_ringbuffer_kunit_test [ 45.822759] 1..1 [ 45.824001] # test_readerwriter: running for 10000 ms [ 45.825762] # test_readerwriter: start thread 001 (writer) [ 45.826187] # test_readerwriter: start thread 002 (writer) [ 45.826607] # test_readerwriter: start thread 003 (writer) [ 45.826881] # test_readerwriter: start thread 004 (writer) [ 45.827193] # test_readerwriter: start thread 005 (writer) [ 45.827512] # test_readerwriter: start thread 006 (writer) [ 45.827724] # test_readerwriter: start thread 007 (writer) [ 45.827951] # test_readerwriter: start thread 008 (writer) [ 45.828200] # test_readerwriter: start thread 009 (writer) [ 45.828353] # test_readerwriter: start thread 010 (writer) [ 45.828548] # test_readerwriter: starting test [ 45.828553] # test_readerwriter: start thread 011 (writer) [ 45.828575] # test_readerwriter: start reader [ 45.828662] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=15 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\x80O\x81\x88\xff\xff [ 45.835013] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=16 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\x01 [ 45.837261] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=17 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\x01 [ 45.837415] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=18 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.841872] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=19 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.844515] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=20 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.844663] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=21 size=1111638594 text= [ 45.844816] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=22 size=1111638594 text= [ 45.849842] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=23 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.849990] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=24 size=1111638594 text= [ 55.841113] # test_readerwriter: end reader: read=14 seq=28 [ 55.841869] # test_readerwriter: completed test [ 55.846197] # test_readerwriter: end thread 011: wrote=15338812 [ 55.847027] # test_readerwriter: end thread 010: wrote=13113829 [ 55.847838] # test_readerwriter: end thread 009: wrote=16786746 [ 55.848469] # test_readerwriter: end thread 008: wrote=14555662 [ 55.849240] # test_readerwriter: end thread 007: wrote=13117536 [ 55.849873] # test_readerwriter: end thread 006: wrote=13147885 [ 55.850478] # test_readerwriter: end thread 005: wrote=16799892 [ 55.851085] # test_readerwriter: end thread 004: wrote=14468908 [ 55.851692] # test_readerwriter: end thread 003: wrote=16795798 [ 55.852311] # test_readerwriter: end thread 002: wrote=15430923 [ 55.852918] # test_readerwriter: end thread 001: wrote=13106357 [ 55.853645] # test_readerwriter.speed: slow [ 55.853681] not ok 1 test_readerwriter [ 55.854080] not ok 1 printk-ringbuffer [ 202.098871] KTAP version 1 [ 202.099389] # Subtest: printk-ringbuffer [ 202.099901] # module: printk_ringbuffer_kunit_test [ 202.100039] 1..1 [ 202.103458] # test_readerwriter: running for 10000 ms [ 202.105324] # test_readerwriter: start thread 001 (writer) [ 202.106870] # test_readerwriter: start thread 002 (writer) [ 202.107413] # test_readerwriter: start thread 003 (writer) [ 202.107805] # test_readerwriter: start thread 004 (writer) [ 202.108256] # test_readerwriter: start thread 005 (writer) [ 202.108486] # test_readerwriter: start thread 006 (writer) [ 202.108777] # test_readerwriter: start thread 007 (writer) [ 202.109017] # test_readerwriter: start thread 008 (writer) [ 202.109608] # test_readerwriter: start thread 009 (writer) [ 202.110028] # test_readerwriter: starting test [ 202.110039] # test_readerwriter: start thread 011 (writer) [ 202.110054] # test_readerwriter: start reader [ 202.110138] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=5 size=1111638594 text= [ 202.110279] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=8 size=1111638594 text= [ 202.110407] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=9 size=94 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 202.110792] # test_readerwriter: start thread 010 (writer) [ 202.111323] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=10 size=1111638594 text= [ 202.120582] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=12 size=1111638594 text= [ 212.257479] # test_readerwriter: end reader: read=12 seq=16 [ 212.258233] # test_readerwriter: completed test [ 212.259613] # test_readerwriter: end thread 011: wrote=13062252 [ 212.260418] # test_readerwriter: end thread 010: wrote=13059061 [ 212.261766] # test_readerwriter: end thread 009: wrote=16683360 [ 212.262379] # test_readerwriter: end thread 008: wrote=16680568 [ 212.263016] # test_readerwriter: end thread 007: wrote=16687096 [ 212.263644] # test_readerwriter: end thread 006: wrote=16646963 [ 212.264265] # test_readerwriter: end thread 005: wrote=16708452 [ 212.264878] # test_readerwriter: end thread 004: wrote=13065967 [ 212.265531] # test_readerwriter: end thread 003: wrote=13090840 [ 212.266098] # test_readerwriter: end thread 002: wrote=13074259 [ 212.266695] # test_readerwriter: end thread 001: wrote=13083747 [ 212.267471] # test_readerwriter.speed: slow [ 212.267502] not ok 1 test_readerwriter [ 212.268136] not ok 1 printk-ringbuffer It is interesting that it did read the same size=XXX values for several seq= numbers. It was 1111638594 in two independent runs. 1st run: BAD RECORD: seq=15 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\x80O\x81\x88\xff\xff [ 45.835013] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=16 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\x01 [ 45.837261] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=17 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB\x01 [ 45.837415] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=18 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.841872] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=19 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.844515] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=20 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.844663] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=21 size=1111638594 text= [ 45.844816] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=22 size=1111638594 text= [ 45.849842] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=23 size=217 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 45.849990] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=24 size=1111638594 text= 2nd run: triggered by: echo 1 > /sys/kernel/debug/kunit/printk-ringbuffer/run BAD RECORD: seq=5 size=1111638594 text= [ 202.110279] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=8 size=1111638594 text= [ 202.110407] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=9 size=94 text=BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB [ 202.110792] # test_readerwriter: start thread 010 (writer) [ 202.111323] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=10 size=1111638594 text= [ 202.120582] # test_readerwriter: EXPECTATION FAILED at kernel/printk/printk_ringbuffer_kunit_test.c:80 BAD RECORD: seq=12 size=1111638594 text= Best Regards, Petr