From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: Fix preempt-rt on AT91 Date: Tue, 8 Mar 2016 19:39:10 +0100 Message-ID: <20160308183910.GD5845@piout.net> References: <1452997394-8554-1-git-send-email-alexandre.belloni@free-electrons.com> <20160118174259.GC12309@linutronix.de> <20160305113553.GB21216@piout.net> <20160308110639.GC21842@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Thomas Gleixner , Boris Brezillon , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Nicolas Ferre To: Sebastian Andrzej Siewior Return-path: Content-Disposition: inline In-Reply-To: <20160308110639.GC21842@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-rt-users.vger.kernel.org Hi, On 08/03/2016 at 12:06:39 +0100, Sebastian Andrzej Siewior wrote : > I sucked this in. It seems to work. What remains that free_irq() thingy: > |WARNING: CPU: 0 PID: 0 at kernel/irq/manage.c:1541 __free_irq+0xb4/0x2e0() > |Trying to free already-free IRQ 16 > |CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.4-rt10+ #219 > |Hardware name: Atmel SAMA5 > |[] (unwind_backtrace) from [] (show_stack+0x10/0x14) > |[] (show_stack) from [] (warn_slowpath_common+0x80/0xac) > |[] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x30/0x40) > |[] (warn_slowpath_fmt) from [] (__free_irq+0xb4/0x2e0) > |[] (__free_irq) from [] (free_irq+0x30/0x4c) > |[] (free_irq) from [] (pit_clkevt_shutdown+0x24/0x2c) > |[] (pit_clkevt_shutdown) from [] (clockevents_switch_state+0x60/0x130) > |---[ end trace 0000000000000001 ]--- > > which is a different problem and was there. The new thing is this: > > |WARNING: CPU: 0 PID: 1 at kernel/locking/rtmutex.c:2062 rt_mutex_trylock+0x30/0x108) > |Modules linked in: > |CPU: 0 PID: 1 Comm: swapper Tainted: G W 4.4.4-rt10+ #219 > |Hardware name: Atmel SAMA5 > |[] (unwind_backtrace) from [] (show_stack+0x10/0x14) > |[] (show_stack) from [] (warn_slowpath_common+0x80/0xac) > |[] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) > |[] (warn_slowpath_null) from [] (rt_mutex_trylock+0x30/0x108) > |[] (rt_mutex_trylock) from [] (rt_spin_trylock_irqsave+0x10/0x1c) > |[] (rt_spin_trylock_irqsave) from [] (clk_enable_lock+0x18/0x114) > |[] (clk_enable_lock) from [] (clk_disable+0x1c/0x34) > |[] (clk_disable) from [] (tc_shutdown+0x34/0x3c) > |[] (tc_shutdown) from [] (tc_set_oneshot+0x20/0x50) > |[] (tc_set_oneshot) from [] (clockevents_switch_state+0xd4/0x130) > |[] (clockevents_switch_state) from [] (tick_switch_to_oneshot+0x48/0xb8) > |[] (tick_switch_to_oneshot) from [] (hrtimer_run_queues+0x48/0x108) > |[] (hrtimer_run_queues) from [] (update_process_times+0x2c/0x64) > |[] (update_process_times) from [] (tick_handle_periodic+0x1c/0x90) > |[] (tick_handle_periodic) from [] (ch2_irq+0x20/0x28) > |[] (ch2_irq) from [] (handle_irq_event_percpu+0x74/0x16c) > > Is it possible to drop this disable/enable clock on the switch from pit > to one shot mode? > Both are things to work on. In the mean time, I'm using the following patch: https://github.com/alexandrebelloni/linux/commit/3a2eae463fce18ae815b887a5c9ca1a657b180ac I understood from http://lkml.iu.edu/hypermail/linux/kernel/1601.2/00941.html that this was not your preferred course of action. Even if that is something that is only seen when using preempt-rt, that is probably something I should push mainline. > >You may also stop at 99a81706526fb167029a940ef1f7bfbe882abd3e which > >should solve the crash but it has not been tested as thoroughly. > > Did you confuse the sha1 with something? This patch is called ("clk: > at91: remove IRQ handling and use polling") and is part of the series > you gave (patch #3). > Yeah, what I meant is that you could stop merging after that patch as this is the one solving the crash. -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com