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Tue, 26 Jan 2021 07:58:35 -0800 (PST) Date: Wed, 27 Jan 2021 00:58:33 +0900 From: Sergey Senozhatsky To: Qais Yousef Cc: Sergey Senozhatsky , Petr Mladek , Thomas Gleixner , Steven Rostedt , John Ogness , "Peter Zijlstra (Intel)" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] Fix BUG: Invalid wait context in hrtimer_interrupt() Message-ID: References: <20210123233741.3614408-1-qais.yousef@arm.com> <20210126145917.r64vzibgpiwyuake@e107158-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210126145917.r64vzibgpiwyuake@e107158-lin> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (21/01/26 14:59), Qais Yousef wrote: > On 01/26/21 13:46, Sergey Senozhatsky wrote: > > On (21/01/23 23:37), Qais Yousef wrote: [..] > I reported it here: https://lore.kernel.org/lkml/20210114124512.mg3vexudfmoadef5@e107158-lin/ > > # [67628.388606] hrtimer: interrupt took 304720 ns > [67628.393546] > [67628.393550] ============================= > [67628.393554] [ BUG: Invalid wait context ] > [67628.393557] 5.11.0-rc3-00019-g86be331946f7 #37 Not tainted > [67628.393560] ----------------------------- > [67628.393563] sugov:0/192 is trying to lock: > [67628.393566] ffff000800b1d898 (&port_lock_key){-.-.}-{3:3}, at: pl011_console_write+0x138/0x218 > [67628.393581] other info that might help us debug this: > [67628.393584] context-{2:2} > [67628.393586] 4 locks held by sugov:0/192: > [67628.393589] #0: ffff0008059cb720 (&sg_policy->work_lock){+.+.}-{4:4}, at: sugov_work+0x58/0x88 > [67628.393603] #1: ffff800015446f20 (prepare_lock){+.+.}-{4:4}, at: clk_prepare_lock+0x34/0xb0 > [67628.393618] #2: ffff8000152aaa60 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x12c/0x310 > [67628.393632] #3: ffff8000152aab88 (console_owner){-.-.}-{0:0}, at: console_unlock+0x190/0x6d8 > [67628.393646] stack backtrace: > [67628.393649] CPU: 0 PID: 192 Comm: sugov:0 Not tainted 5.11.0-rc3-00019-g86be331946f7 #37 > [67628.393653] Hardware name: ARM Juno development board (r2) (DT) > [67628.393656] Call trace: > [67628.393659] dump_backtrace+0x0/0x1b0 > [67628.393661] show_stack+0x20/0x70 > [67628.393664] dump_stack+0xf8/0x168 > [67628.393666] __lock_acquire+0x964/0x1c88 > [67628.393669] lock_acquire+0x26c/0x500 > [67628.393671] _raw_spin_lock+0x64/0x88 > [67628.393674] pl011_console_write+0x138/0x218 > [67628.393677] console_unlock+0x2c4/0x6d8 > [67628.393680] vprintk_emit+0x134/0x310 > [67628.393682] vprintk_default+0x40/0x50 > [67628.393685] vprintk_func+0xfc/0x2b0 > [67628.393687] printk+0x68/0x90 > [67628.393690] hrtimer_interrupt+0x24c/0x250 > [67628.393693] arch_timer_handler_phys+0x3c/0x50 > [67628.393695] handle_percpu_devid_irq+0xd8/0x460 > [67628.393698] generic_handle_irq+0x38/0x50 > [67628.393701] __handle_domain_irq+0x6c/0xc8 > [67628.393704] gic_handle_irq+0xb0/0xf0 > [67628.393706] el1_irq+0xb4/0x180 > [67628.393709] _raw_spin_unlock_irqrestore+0x58/0xa8 > [67628.393712] hrtimer_start_range_ns+0x1b0/0x420 > [67628.393715] msg_submit+0x100/0x108 > [67628.393717] mbox_send_message+0x84/0x128 > [67628.393720] scpi_send_message+0x11c/0x2a8 > [67628.393723] scpi_dvfs_set_idx+0x48/0x70 > [67628.393726] scpi_dvfs_set_rate+0x60/0x78 > [67628.393728] clk_change_rate+0x184/0x8a8 > [67628.393731] clk_core_set_rate_nolock+0x1c0/0x280 > [67628.393734] clk_set_rate+0x40/0x98 > [67628.393736] scpi_cpufreq_set_target+0x40/0x68 > [67628.393739] __cpufreq_driver_target+0x1a0/0x5d0 Thanks. > > Why is it invalid? Is this... -rt kernel, perhaps? > > No I was running on Linus master at the time. > > AFAIU printk will hold the console lock which could sleep in interrupt context. > > Did I miss something? printk() is not permitted to sleep/schedule/etc and it never does. Generally it should be OK to call it from IRQ (module recursion paths). -ss