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([2402:b801:2840:8200:e4f7:baaa:ff2a:bf24]) by smtp.gmail.com with ESMTPSA id e2sm17777231pgl.38.2020.09.23.06.04.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Sep 2020 06:04:21 -0700 (PDT) To: linux-amlogic@lists.infradead.org, linux-mmc@vger.kernel.org From: Brad Harper Cc: linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH] mmc: host: meson-gx-mmc: fix possible deadlock condition for preempt_rt Message-ID: <24a844c3-c2e0-c735-ccb7-83736218b548@gmail.com> Date: Wed, 23 Sep 2020 23:04:15 +1000 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Force threaded interrupts for meson_mmc_irq to prevent possible deadlock condition during mmc operations when using preempt_rt with 5.9.0-rc3-rt3 patches on arm64. Using meson-gx-mmc with an emmc device on Hardkernel Odroid N2+ configured with preempt_rt resulted in the soc becoming unresponsive.  With lock checking enabled the below inconsistent lock state was observed during boot. After some discussions with tglx in IRC #linux-rt the attached patch was suggested to remove IRQF_ONESHOT from request_threaded_irq. This has been tested and confirmed by me to resolve both the unresponsive soc and the inconsistent lock state warning when using 5.9.0-rc3-rt3 on arm64 Odroid N2+. Further review and testing is required to ensure there are no adverse impacts or concerns and that is the correct method to resolve the problem.  I will continue to test on various amlogic devices with both standard mainline low latency kernel and preempt_rt kernel with -rt patches. [ 7.858446] ================================ [ 7.858448] WARNING: inconsistent lock state [ 7.858450] 5.9.0-rc3-rt3+ #33 Not tainted [ 7.858453] -------------------------------- [ 7.858456] inconsistent {IN-HARDIRQ-R} -> {HARDIRQ-ON-W} usage. [ 7.858459] swapper/0/1 [HC0[0]:SC0[0]:HE1:SE1] takes: [ 7.858465] ffff80001219f4d8 (&trig->leddev_list_lock){+?.+}-{0:0}, at: led_trigger_set+0x104/0x270 [ 7.858482] {IN-HARDIRQ-R} state was registered at: [ 7.858484] lock_acquire+0xec/0x468 [ 7.858491] rt_read_lock+0xb0/0x108 [ 7.858497] led_trigger_event+0x34/0x88 [ 7.858501] mmc_request_done+0x3f0/0x450 [ 7.858505] meson_mmc_irq+0x284/0x378 [ 7.858511] __handle_irq_event_percpu+0xcc/0x4a8 [ 7.858515] handle_irq_event_percpu+0x60/0xb0 [ 7.858519] handle_irq_event+0x50/0x108 [ 7.858522] handle_fasteoi_irq+0xd0/0x180 [ 7.858527] generic_handle_irq+0x38/0x50 [ 7.858530] __handle_domain_irq+0x6c/0xc8 [ 7.858533] gic_handle_irq+0x5c/0xb8 [ 7.858537] el1_irq+0xbc/0x180 [ 7.858540] arch_cpu_idle+0x28/0x38 [ 7.858544] default_idle_call+0x90/0x3f0 [ 7.858547] do_idle+0x250/0x268 [ 7.858551] cpu_startup_entry+0x2c/0x78 [ 7.858554] rest_init+0x1b0/0x284 [ 7.858559] arch_call_rest_init+0x18/0x24 [ 7.858565] start_kernel+0x550/0x588 [ 7.858569] irq event stamp: 1925495 [ 7.858571] hardirqs last enabled at (1925495): [] _raw_spin_unlock_irqrestore+0xa4/0xb0 [ 7.858576] hardirqs last disabled at (1925494): [] _raw_spin_lock_irqsave+0xa8/0xb8 [ 7.858580] softirqs last enabled at (1857856): [] bdi_register_va+0x114/0x368 [ 7.858586] softirqs last disabled at (1857849): [] bdi_register_va+0x114/0x368 [ 7.858590] other info that might help us debug this: [ 7.858592] Possible unsafe locking scenario: [ 7.858594] CPU0 [ 7.858595] ---- [ 7.858597] lock(&trig->leddev_list_lock); [ 7.858600] [ 7.858602] lock(&trig->leddev_list_lock); [ 7.858604] *** DEADLOCK *** [ 7.858606] 3 locks held by swapper/0/1: [ 7.858609] #0: ffff80001219eb30 (leds_list_lock){++++}-{0:0}, at: led_trigger_register+0xf4/0x1c0 [ 7.858619] #1: ffff0000b0696a70 (&led_cdev->trigger_lock){+.+.}-{0:0}, at: led_trigger_register+0x134/0x1c0 [ 7.858629] #2: ffff800011fb83d0 (rcu_read_lock){....}-{1:2}, at: rt_write_lock+0x8/0x108 [ 7.858637] stack backtrace: [ 7.858640] CPU: 5 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc3-rt3+ #33 [ 7.858643] Hardware name: Hardkernel ODROID-N2Plus (DT) [ 7.858646] Call trace: [ 7.858647] dump_backtrace+0x0/0x1e8 [ 7.858650] show_stack+0x20/0x30 [ 7.858653] dump_stack+0xf0/0x164 [ 7.858659] print_usage_bug+0x2b4/0x2c0 [ 7.858662] mark_lock+0x2e8/0x360 [ 7.858665] __lock_acquire+0x238/0x1858 [ 7.858669] lock_acquire+0xec/0x468 [ 7.858672] rt_write_lock+0xb0/0x108 [ 7.858675] led_trigger_set+0x104/0x270 [ 7.858678] led_trigger_register+0x180/0x1c0 [ 7.858681] heartbeat_trig_init+0x28/0x5c [ 7.858686] do_one_initcall+0x90/0x4bc [ 7.858690] kernel_init_freeable+0x2cc/0x338 [ 7.858694] kernel_init+0x1c/0x11c [ 7.858697] ret_from_fork+0x10/0x34 Signed-off-by: Brad Harper ---  drivers/mmc/host/meson-gx-mmc.c | 2 +-  1 file changed, 1 insertion(+), 1 deletion(-)                 goto err_init_clk; -- 2.20.1 diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c index 08a3b1c05..130ac134d 100644 --- a/drivers/mmc/host/meson-gx-mmc.c +++ b/drivers/mmc/host/meson-gx-mmc.c @@ -1139,7 +1139,7 @@ static int meson_mmc_probe(struct platform_device *pdev)                host->regs + SD_EMMC_IRQ_EN);         ret = request_threaded_irq(host->irq, meson_mmc_irq, -                                  meson_mmc_irq_thread, IRQF_ONESHOT, +                                  meson_mmc_irq_thread, 0,                                    dev_name(&pdev->dev), host);         if (ret)