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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2DCE1C4332F for ; Mon, 28 Mar 2022 11:29:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241351AbiC1LbG (ORCPT ); Mon, 28 Mar 2022 07:31:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241410AbiC1Laa (ORCPT ); Mon, 28 Mar 2022 07:30:30 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90D2A56401; Mon, 28 Mar 2022 04:24:15 -0700 (PDT) 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 C304EB80D13; Mon, 28 Mar 2022 11:24:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A06EC340EC; Mon, 28 Mar 2022 11:24:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648466653; bh=cP8eXvoILvKyCmNwhZq587enkFd13QhBz2x9z8aEujE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G3orq/ejB0N/RffiHPIffUOitiqHXuWYU861rgbaOAVqly17IL9HqmA36aaulp0FK zd0pMtvdIvCkZ0/zt3l/fJOtYvvSK5lhlJP3O20lMXP3L/RnlRfeZa/dR9LiC6l3/1 s/DU5MZWqWLUwebHCUF+UxJSJtEmL4nYbePHI/e9+x6wTLd++mDJEcNZO+VL32lmgq Epq6ec+H1u5s45hywGok1nWgtZ5wbY6tQDbf4NmN2InkGI7lMaft3Y8P/POT+vkEn0 oGlBfg1zYhm/VppDpQ2+fJ5K5CYVGD3keaN06n4xdNjfPi1p+OJNFQQe6mYgF73cCq WxSHny3k5H36Q== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Darren Hart , "Rafael J . Wysocki" , Sasha Levin , rafael@kernel.org, ying.huang@intel.com, rdunlap@infradead.org, linux-acpi@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 14/16] ACPI/APEI: Limit printable size of BERT table data Date: Mon, 28 Mar 2022 07:23:43 -0400 Message-Id: <20220328112345.1556601-14-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220328112345.1556601-1-sashal@kernel.org> References: <20220328112345.1556601-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Darren Hart [ Upstream commit 3f8dec116210ca649163574ed5f8df1e3b837d07 ] Platforms with large BERT table data can trigger soft lockup errors while attempting to print the entire BERT table data to the console at boot: watchdog: BUG: soft lockup - CPU#160 stuck for 23s! [swapper/0:1] Observed on Ampere Altra systems with a single BERT record of ~250KB. The original bert driver appears to have assumed relatively small table data. Since it is impractical to reassemble large table data from interwoven console messages, and the table data is available in /sys/firmware/acpi/tables/data/BERT limit the size for tables printed to the console to 1024 (for no reason other than it seemed like a good place to kick off the discussion, would appreciate feedback from existing users in terms of what size would maintain their current usage model). Alternatively, we could make printing a CONFIG option, use the bert_disable boot arg (or something similar), or use a debug log level. However, all those solutions require extra steps or change the existing behavior for small table data. Limiting the size preserves existing behavior on existing platforms with small table data, and eliminates the soft lockups for platforms with large table data, while still making it available. Signed-off-by: Darren Hart Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/acpi/apei/bert.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/acpi/apei/bert.c b/drivers/acpi/apei/bert.c index 1155fb9dcc3a..9f4a82ef9bc4 100644 --- a/drivers/acpi/apei/bert.c +++ b/drivers/acpi/apei/bert.c @@ -29,6 +29,7 @@ #undef pr_fmt #define pr_fmt(fmt) "BERT: " fmt +#define ACPI_BERT_PRINT_MAX_LEN 1024 static int bert_disable; @@ -58,8 +59,11 @@ static void __init bert_print_all(struct acpi_bert_region *region, } pr_info_once("Error records from previous boot:\n"); - - cper_estatus_print(KERN_INFO HW_ERR, estatus); + if (region_len < ACPI_BERT_PRINT_MAX_LEN) + cper_estatus_print(KERN_INFO HW_ERR, estatus); + else + pr_info_once("Max print length exceeded, table data is available at:\n" + "/sys/firmware/acpi/tables/data/BERT"); /* * Because the boot error source is "one-time polled" type, -- 2.34.1