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 89B2FC28CF5 for ; Wed, 26 Jan 2022 10:52:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240245AbiAZKwV (ORCPT ); Wed, 26 Jan 2022 05:52:21 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:51177 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240258AbiAZKwQ (ORCPT ); Wed, 26 Jan 2022 05:52:16 -0500 Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id AE10960012; Wed, 26 Jan 2022 10:52:14 +0000 (UTC) From: Miquel Raynal To: David Decotigny , linux-kernel@vger.kernel.org Cc: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra , linux-mtd@lists.infradead.org, David Decotigny Subject: Re: [PATCH RFC v3 1/1] mtd_blkdevs: avoid soft lockups with some mtd/spi devices Date: Wed, 26 Jan 2022 11:52:14 +0100 Message-Id: <20220126105214.882348-1-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220126101120.676021-1-decot+git@google.com> References: MIME-Version: 1.0 X-linux-mtd-patch-notification: thanks X-linux-mtd-patch-commit: b'ca6263a0c9503d98b5aef04ed9b0f3971c66ec4e' Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2022-01-26 at 10:11:20 UTC, David Decotigny wrote: > From: David Decotigny > > With some spi devices, the heavy cpu usage due to polling the spi > registers may lead to netdev timeouts, RCU complaints, etc. This can > be acute in the absence of CONFIG_PREEMPT. This patch allows to give > enough breathing room to avoid those incorrectly detected netdev > timeouts for example. > > Example splat on 5.10.92: > [ 828.399306] rcu: INFO: rcu_sched self-detected stall on CPU > ... > [ 828.419245] Task dump for CPU 1: > [ 828.422465] task:kworker/1:1H state:R running task on cpu 1 stack: 0 pid: 76 ppid: 2 flags:0x0000002a > [ 828.433132] Workqueue: kblockd blk_mq_run_work_fn > [ 828.437820] Call trace: > ... > [ 828.512267] spi_mem_exec_op+0x4d0/0xde0 > [ 828.516184] spi_mem_dirmap_read+0x180/0x39c > [ 828.520443] spi_nor_read_data+0x428/0x7e8 > [ 828.524523] spi_nor_read+0x154/0x214 > [ 828.528172] mtd_read_oob+0x440/0x714 > [ 828.531815] mtd_read+0xac/0x120 > [ 828.535030] mtdblock_readsect+0x178/0x230 > [ 828.539102] mtd_blktrans_work+0x9fc/0xf28 > [ 828.543177] mtd_queue_rq+0x1ac/0x2e4 > [ 828.546827] blk_mq_dispatch_rq_list+0x2cc/0xa44 > [ 828.551419] blk_mq_do_dispatch_sched+0xb0/0x7cc > [ 828.556010] __blk_mq_sched_dispatch_requests+0x350/0x494 > [ 828.561372] blk_mq_sched_dispatch_requests+0xac/0xe4 > [ 828.566387] __blk_mq_run_hw_queue+0x130/0x254 > [ 828.570806] blk_mq_run_work_fn+0x50/0x60 > [ 828.574814] process_one_work+0x578/0xf1c > [ 828.578814] worker_thread+0x5dc/0xea0 > [ 828.582547] kthread+0x270/0x2d4 > [ 828.585765] ret_from_fork+0x10/0x30 > > > Signed-off-by: David Decotigny > Reviewed-by: Richard Weinberger Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks. Miquel