From patchwork Tue Oct 19 15:53:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Righi X-Patchwork-Id: 1543443 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=canonical.com header.i=@canonical.com header.a=rsa-sha256 header.s=20210705 header.b=bQz6L0Kk; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4HYdZL645fz9sNH for ; Wed, 20 Oct 2021 02:53:29 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1mcrQS-0002DZ-EG; Tue, 19 Oct 2021 15:53:16 +0000 Received: from smtp-relay-internal-0.internal ([10.131.114.225] helo=smtp-relay-internal-0.canonical.com) by huckleberry.canonical.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1mcrQQ-0002DM-BF for kernel-team@lists.ubuntu.com; Tue, 19 Oct 2021 15:53:14 +0000 Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id 253343FFFE for ; Tue, 19 Oct 2021 15:53:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1634658794; bh=JdNgKu3D067+39G6X2IHS17ZmKHNSTH2Dm873CoSDwQ=; h=From:To:Subject:Date:Message-Id:MIME-Version; b=bQz6L0KkQEeKd7SEeCIu46OpAzxMB6981ZFHo34qn1d0ZA6czw4okr07/vncCRtID NNhBwsWAy4ZLDLPDgLpldUsuC2NPnFjfB9/wEN6Dk8ZBaFnU0H+dqgtkS5urWHHMx2 OPOMH4d600vjyzcd79s5taBKVdtBeVvRXLg99OERdN65BQoCeZY/Civ+BAWP4IZDHu WbdSQTBYc+XC8YYKbhT37EyRg8h7IiTr9TwbWbitlyq22SbtdlcoDxcy35w4+gM5ru v6U/IPHfB4gPwR1ZOhHFu3En/GJYR6sEINzkO1JpLT7PM3rxq4EAmSoMWcknvAppAE 9OJFKJGE3FvQQ== Received: by mail-ed1-f72.google.com with SMTP id f4-20020a50e084000000b003db585bc274so17986301edl.17 for ; Tue, 19 Oct 2021 08:53:14 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:subject:date:message-id:mime-version :content-transfer-encoding; bh=JdNgKu3D067+39G6X2IHS17ZmKHNSTH2Dm873CoSDwQ=; b=TjAJgZNNMUM7Gge96W/6ItRAbZzThwunOL1LDEim7cHZJ+fDA7H7JeFPS04E68SmUK xPcIV9rN0uJWl9veTp2NMGgDjtqT9TDo6SWqgwQ0z4VNcZbOmVAiE74ClbXUahupkCsC wdyHJcQ1msxAG9/Dbv8T7Tf/OPeJV/g0meK7lJrm9zoPmItATA5E0dltuaZC1r69d3nQ XNo5BgbpRRlG/vptUpoMEJyaRw1trmM/bUmqh9vt9syitIEasPhUD93cnWXUdkjiIi6/ ymMFr+0BKiv7IkpW3OTfvp/aHbUD+Z+7xT5KC1vWQogki0j2v6HuEfyuZsnCLXq7VlOx gGzQ== X-Gm-Message-State: AOAM530qCzqpJfLKHptqzMEUbWGAHbD4qiL0xzdBR5aS73z/Ji8bobYS 3MEy+HaYBSm6gIRUKbRMS91HtZYxnpW3IEHsz2qpok9ZuHe3CQqlNc3XSRlTnDIjNXp09/7VNH3 Vbb0hDq99nTBkjK3+hX0YEWqlhrguwcbUC23hf6dpqA== X-Received: by 2002:a17:906:8a79:: with SMTP id hy25mr38548742ejc.371.1634658793830; Tue, 19 Oct 2021 08:53:13 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz83ibXsopDQuIwvmpB69esgZxZdPMihJ5wPFgA6PQBOWJnb0ZRsuV1gA9F8Iuf1GBWYNGSuQ== X-Received: by 2002:a17:906:8a79:: with SMTP id hy25mr38548706ejc.371.1634658793533; Tue, 19 Oct 2021 08:53:13 -0700 (PDT) Received: from arighi-desktop.homenet.telecomitalia.it ([2001:67c:1560:8007::aac:c1b6]) by smtp.gmail.com with ESMTPSA id bq4sm10463682ejb.43.2021.10.19.08.53.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Oct 2021 08:53:13 -0700 (PDT) From: Andrea Righi To: kernel-team@lists.ubuntu.com Subject: [SRU][I][PATCH 0/1] kernel panic: NULL pointer dereference in wb_timer_f() Date: Tue, 19 Oct 2021 17:53:08 +0200 Message-Id: <20211019155309.65576-1-andrea.righi@canonical.com> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" BugLink: https://bugs.launchpad.net/bugs/1947557 [Impact] It is possible to trigger a kernel panic with the latest impish kernel running systemd autopkgtest using --enable-kvm with the test instances created by systemd during the autotest. The panic happens in the host, not in the guest VM executed by systemd. [Test case] Add --enable-kvm to the options in test/testdata/test-functions (systemd), run `sudo autopkgtest . -- null`, wait for the panic to happen. [Fix] https://lore.kernel.org/lkml/YW6N2qXpBU3oc50q@arighi-desktop/T/#u [Regression potential] The fix is addressing a race in the block layer (in the buffered write throttling code - block/blk-wbt.c) between a disk being released and the timer callback that periodically checks if the latency for a specific block device has been exceeded. If the fix is not correct we may still have a race in this code, that can still show potential kernel panics in the block layer subsystem. Acked-by: Kamal Mostafa