Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754265Ab1FTM5h (ORCPT ); Mon, 20 Jun 2011 08:57:37 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:43305 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752422Ab1FTM5g (ORCPT ); Mon, 20 Jun 2011 08:57:36 -0400 Date: Mon, 20 Jun 2011 13:57:15 +0100 From: Russell King - ARM Linux To: Santosh Shilimkar Cc: Peter Zijlstra , Thomas Gleixner , linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [RFC PATCH] ARM: smp: Fix the CPU hotplug race with scheduler. Message-ID: <20110620125715.GK2082@n2100.arm.linux.org.uk> References: <20110620101438.GD2082@n2100.arm.linux.org.uk> <4DFF20B3.7010209@ti.com> <20110620104415.GF2082@n2100.arm.linux.org.uk> <4DFF255E.5030308@ti.com> <20110620111336.GG2082@n2100.arm.linux.org.uk> <4DFF2E37.8030602@ti.com> <20110620114019.GH2082@n2100.arm.linux.org.uk> <4DFF3454.30507@ti.com> <20110620121939.GI2082@n2100.arm.linux.org.uk> <4DFF3C95.1080903@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DFF3C95.1080903@ti.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1640 Lines: 46 On Mon, Jun 20, 2011 at 05:57:01PM +0530, Santosh Shilimkar wrote: > On 6/20/2011 5:49 PM, Russell King - ARM Linux wrote: >> On Mon, Jun 20, 2011 at 05:21:48PM +0530, Santosh Shilimkar wrote: >>> On 6/20/2011 5:10 PM, Russell King - ARM Linux wrote: > > [...] > >>> >>> Any pointers on the other question about "why we need to enable >>> interrupts before the CPU is ready?" >> >> To ensure that things like the delay loop calibration and twd calibration >> can run, though that looks like it'll run happily enough with the boot >> CPU updating jiffies. >> > I guessed it and had same point as above. Calibration will still > work. > >> However, I'm still not taking your patch because I believe its just >> papering over the real issue, which is not as you describe. >> >> You first need to work out why the spinlock lockup detection is firing >> after just 61us rather than the full 1s and fix that. >> > This is possibly because of my script which doesn't wait for 1 > second. How could a userspace script affect the internal behaviour of spin_lock() and the spinlock lockup detector? > Latest mainline kernel with omap2plus_defconfig and below simple script > to trigger the failure. > > ------------- > while true > do > echo 0 > /sys/devices/system/cpu/cpu1/online > echo 1 > /sys/devices/system/cpu/cpu1/online > done Thanks, I'll give it a go here and see if I can debug it further. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/