From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 853D2C25B0F for ; Sun, 14 Aug 2022 16:23:22 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4M5N4m6bRPz3drc for ; Mon, 15 Aug 2022 02:23:20 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=MfSo1YXX; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4601:e00::1; helo=ams.source.kernel.org; envelope-from=sashal@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=MfSo1YXX; dkim-atps=neutral Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4M5N3g0gPXz3bqn for ; Mon, 15 Aug 2022 02:22:22 +1000 (AEST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 6C284B80B74; Sun, 14 Aug 2022 16:22:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E0643C433C1; Sun, 14 Aug 2022 16:22:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660494139; bh=E3o1NL9M7MMxOvh5P8/+p5pkrfDEPsN6Qcy7OMxtyBg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MfSo1YXXJTUSvczW3FI6AfXK86tk3640KH31Iz4ppxlue8kaHyV6RvQRuI4NtmNO2 TMKtabmKU3R59IivrI6nwKfrXVYSqVEmVDzFDCPfJtM4XRFAv+/LJvm4g67keO4kCh wBBIgtd2h/39K0HEjMEVqKE6PXc0PldP6iZLeR1pBW8HquIAaKwfu9pYuN8D5daa46 hWQNr3cM5Ztl3DPVXDJcnKL1i0IuEm41S8H33KIekS59m8S6bZzPlYZziKc/bEZ4FH v8G6jIpOmn2mo1scEJ3anmY78hvA0bt8qs0D8g09Y9oIjyT1IED+V4hmgLyM97eUPD 3KKMbzggDGDNA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 5.19 30/48] powerpc/pseries/mobility: set NMI watchdog factor during an LPM Date: Sun, 14 Aug 2022 12:19:23 -0400 Message-Id: <20220814161943.2394452-30-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220814161943.2394452-1-sashal@kernel.org> References: <20220814161943.2394452-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sasha Levin , robh@kernel.org, Jason@zx2c4.com, nathanl@linux.ibm.com, corbet@lwn.net, mchehab+huawei@kernel.org, linux-doc@vger.kernel.org, haren@linux.ibm.com, linuxppc-dev@lists.ozlabs.org, Nicholas Piggin , gpiccoli@igalia.com, linux@dominikbrodowski.net, ying.huang@intel.com, akpm@linux-foundation.org, Laurent Dufour , will@kernel.org, jsavitz@redhat.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Laurent Dufour [ Upstream commit 118b1366930c8c833b8b36abef657f40d4e26610 ] During an LPM, while the memory transfer is in progress on the arrival side, some latencies are generated when accessing not yet transferred pages on the arrival side. Thus, the NMI watchdog may be triggered too frequently, which increases the risk to hit an NMI interrupt in a bad place in the kernel, leading to a kernel panic. Disabling the Hard Lockup Watchdog until the memory transfer could be a too strong work around, some users would want this timeout to be eventually triggered if the system is hanging even during an LPM. Introduce a new sysctl variable nmi_watchdog_factor. It allows to apply a factor to the NMI watchdog timeout during an LPM. Just before the CPUs are stopped for the switchover sequence, the NMI watchdog timer is set to watchdog_thresh + factor% A value of 0 has no effect. The default value is 200, meaning that the NMI watchdog is set to 30s during LPM (based on a 10s watchdog_thresh value). Once the memory transfer is achieved, the factor is reset to 0. Setting this value to a high number is like disabling the NMI watchdog during an LPM. Signed-off-by: Laurent Dufour Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220713154729.80789-5-ldufour@linux.ibm.com Signed-off-by: Sasha Levin --- Documentation/admin-guide/sysctl/kernel.rst | 12 ++++++ arch/powerpc/platforms/pseries/mobility.c | 43 +++++++++++++++++++++ 2 files changed, 55 insertions(+) diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index ddccd1077462..9b7fa1baf225 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -592,6 +592,18 @@ to the guest kernel command line (see Documentation/admin-guide/kernel-parameters.rst). +nmi_wd_lpm_factor (PPC only) +============================ + +Factor to apply to the NMI watchdog timeout (only when ``nmi_watchdog`` is +set to 1). This factor represents the percentage added to +``watchdog_thresh`` when calculating the NMI watchdog timeout during an +LPM. The soft lockup timeout is not impacted. + +A value of 0 means no change. The default value is 200 meaning the NMI +watchdog is set to 30s (based on ``watchdog_thresh`` equal to 10). + + numa_balancing ============== diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c index 78f3f74c7056..cbe0989239bf 100644 --- a/arch/powerpc/platforms/pseries/mobility.c +++ b/arch/powerpc/platforms/pseries/mobility.c @@ -48,6 +48,39 @@ struct update_props_workarea { #define MIGRATION_SCOPE (1) #define PRRN_SCOPE -2 +#ifdef CONFIG_PPC_WATCHDOG +static unsigned int nmi_wd_lpm_factor = 200; + +#ifdef CONFIG_SYSCTL +static struct ctl_table nmi_wd_lpm_factor_ctl_table[] = { + { + .procname = "nmi_wd_lpm_factor", + .data = &nmi_wd_lpm_factor, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_douintvec_minmax, + }, + {} +}; +static struct ctl_table nmi_wd_lpm_factor_sysctl_root[] = { + { + .procname = "kernel", + .mode = 0555, + .child = nmi_wd_lpm_factor_ctl_table, + }, + {} +}; + +static int __init register_nmi_wd_lpm_factor_sysctl(void) +{ + register_sysctl_table(nmi_wd_lpm_factor_sysctl_root); + + return 0; +} +device_initcall(register_nmi_wd_lpm_factor_sysctl); +#endif /* CONFIG_SYSCTL */ +#endif /* CONFIG_PPC_WATCHDOG */ + static int mobility_rtas_call(int token, char *buf, s32 scope) { int rc; @@ -665,19 +698,29 @@ static int pseries_suspend(u64 handle) static int pseries_migrate_partition(u64 handle) { int ret; + unsigned int factor = 0; +#ifdef CONFIG_PPC_WATCHDOG + factor = nmi_wd_lpm_factor; +#endif ret = wait_for_vasi_session_suspending(handle); if (ret) return ret; vas_migration_handler(VAS_SUSPEND); + if (factor) + watchdog_nmi_set_timeout_pct(factor); + ret = pseries_suspend(handle); if (ret == 0) post_mobility_fixup(); else pseries_cancel_migration(handle, ret); + if (factor) + watchdog_nmi_set_timeout_pct(0); + vas_migration_handler(VAS_RESUME); return ret; -- 2.35.1