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 X-Spam-Level: X-Spam-Status: No, score=-5.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC1B0C433DB for ; Wed, 13 Jan 2021 10:30:30 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 89A1122CE3 for ; Wed, 13 Jan 2021 10:30:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 89A1122CE3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=iUhHWV47G46orrOjEToyAB9UVqcaMbSKcw6pnIMj/aA=; b=Z2/mRqisvyqGFvnK3poDg50iw b7Qnq2Hxa1C8Kf3WaIB/VFEWyPBP9tCOEo1HM/2wwdqBVKQTtI6oJu3RSvZcwLH4K8T7ifF/mmFGQ 0rkqnn+garVxwIyxScfnRoOrO6oUSuYrlTKy+VDWPzvonFNyCjwT1dfF8DCHG/DxKplKg3G7ixEFY s1XsHf3vZU/4jYV40wmhPLc7VSiJsbiQogiIgDZ4/Z8GK06h6fYOEowvtHKAUeS89IMcnnYSQRgdx ZGDl0e1aB+x1z18kz5zouD7vcFkBcT5UuzlW5gpYLqhdzKRy6FWifAP1c3Jb3K4aR7ifx37LVJ/Ny 3NZkTE8sg==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kzdOU-0008Kh-Tx; Wed, 13 Jan 2021 10:28:50 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kzdOR-0008KE-Sm for linux-arm-kernel@lists.infradead.org; Wed, 13 Jan 2021 10:28:48 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6906423117; Wed, 13 Jan 2021 10:28:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610533726; bh=JI0PFz6eQ+u9O7Pnk3S4wXoYk/y4/8SapPJf7ABmRvk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Sf7gsIAba8M8V7m0kZz8lO/Q5JyNoJD9dh3PKOGXVBsSAB+kWYbR2+utDBBR11eUA IrEHDAtf7E2+6+9G6VpvMRHlbQepnYB0DqDLePkQqz8fT0lUlKssue2K2RtG3PdFN5 qYK6QnJVxvS1Exr0/nffRuDEzjXhNjsZ680z5r754PpxsMzlzAT+D+YyJTTXQZfye7 jgYhIFwfPhdu9vAttdZmeW1XK+3EU4TsFt+yr0SQFD0RbJYw/8y1cEbBa7hzVuaDy7 jjysrJiz4yDDWSNfo1WEM7IXjijfjSiR/ap553CI02y7pz0KUZYKDrVm1DBSz3ldwM /Ix6mEQ8cLCKg== Date: Wed, 13 Jan 2021 10:28:41 +0000 From: Will Deacon To: Sumit Garg Subject: Re: [PATCH] Revert "arm64: Enable perf events based hard lockup detector" Message-ID: <20210113102841.GA11503@willie-the-truck> References: <20210112221855.10666-1-will@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210113_052848_028571_EF437F16 X-CRM114-Status: GOOD ( 17.12 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Lecopzer Chen , Catalin Marinas , Alexandru Elisei , kernel-team@android.com, linux-arm-kernel Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jan 13, 2021 at 12:00:01PM +0530, Sumit Garg wrote: > On Wed, 13 Jan 2021 at 03:49, Will Deacon wrote: > > > > This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5. > > > > lockup_detector_init() makes heavy use of per-cpu variables and must be > > called with preemption disabled. Usually, it's handled early during boot > > in kernel_ionit_freeable(), before SMP has been initialised. > > > > Since we do not know whether or not our PMU interrupt can be signalled > > as an NMI until considerably later in the boot process, the Arm PMU > > driver attempts to re-initialise the lockup detector off the back of a > > device_initcall(). Unfortunately, this is called from preemptible > > context and results in the following splat: > > Can we consider the following fix (compile tested only) to bind the > call to lockup_detector_init() to a particular CPU instead of > reverting the hard lockup detection feature as a whole? I think the revert is the right approach for 5.11, and you still have time to post a new (preferably more than just compile-tested!) version for 5.12. This is a new feature so we have time to get it right. Thanks, Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel