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[52.52.135.65]) by smtp-relay.gmail.com with ESMTPS id 00721157ae682-7e17b446f64sm4902517b3.20.2026.06.01.13.29.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Jun 2026 13:29:10 -0700 (PDT) X-Relaying-Domain: arista.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=Arista-A; t=1780345749; bh=qzcnnb4ft/sHGmWhq3YYu19yrHmbVI8yyzjWSZ/LZK8=; h=Date:From:To:Cc:Subject:From; b=dsjluN2CMjxRnHeBxRFRQuOG/hIdciKtX5vqGx80+kiwfXlMp/V8cUwRSgrgBK6F+ NOUTdNpbTAwjGyqtaLF8kU0HXULGdehLMpd4VOu8p16yA0tNxG5Mts4vTRp8BCYZv6 s+WRP2AqyqEXDKrCEk/qiGze5fmDUmUECcxPYPhKJ9hBSKKcBkrI5jIkUsuCFfS1R0 iC3DjMcmc0I1dMatYdM8nrOiTFEyscY/w+Ja1qnSkQpJvRXt9VdNTTkphvLg2OxL6q 0wNMbOi+pZXXH0FV+dDqHwuN/0wV+/9IK+JABB8cnTjv3tj/lVLimL8WyRpzuukMp0 4heJhQ/fdiQIQ== Received: from vm-ymd.sjc.aristanetworks.com (dhcp-244-52-81.sjc.aristanetworks.com [10.244.52.81]) by smtp.aristanetworks.com (Postfix) with ESMTPS id 42028C265C; Mon, 1 Jun 2026 20:29:09 +0000 (UTC) Date: Mon, 1 Jun 2026 20:29:08 +0000 X-SMTP-Authentication: Allow-List-permitted X-SMTP-Authentication: Allow-List-permitted From: Mohan Yelugoti To: linux-acpi@vger.kernel.org Cc: rafael.j.wysocki@intel.com, mario.limonciello@amd.com, mika.westerberg@linux.intel.com, linux-kernel@vger.kernel.org Subject: [REGRESSION] ACPI: threaded SCI handler causes soft lockup in kdump capture kernel Message-ID: Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Hi, We ship SONiC[0] on top of Debian stable with a small set of patches on top (see [1]). After moving SONiC from Debian bookworm to trixie, we started seeing a regression where the kdump capture kernel hits a soft lockup while collecting the crash dump, so no vmcore is produced. We trigger the original panic in the kernel with: echo c > /proc/sysrq-trigger The capture kernel then boots and hangs. To capture a usable trace rather than waiting indefinitely, I added the following to the capture-kernel command line so that it panics on soft lockup (and dumps backtraces from all CPUs) when the hang is detected: debug=1 loglevel=7 softlockup_all_cpu_backtrace=1 softlockup_panic=1 With those in place, the capture kernel prints: watchdog: BUG: soft lockup - CPU#0 stuck for 26s! [irq/9-acpi:39] CPU: 0 UID: 0 PID: 39 Comm: irq/9-acpi Not tainted 6.12.41+deb13-sonic-amd64 #1 Debian 6.12.41-1 RIP: 0010:acpi_os_read_port+0x30/0xa0 Call Trace: acpi_hw_gpe_read+0x61/0x80 acpi_ev_detect_gpe+0x74/0x180 acpi_ev_gpe_detect+0xe1/0x130 acpi_ev_sci_xrupt_handler+0x1d/0x40 acpi_irq+0x1c/0x40 irq_thread_fn+0x23/0x60 irq_thread+0x1b3/0x2f0 kthread+0xd2/0x100 ret_from_fork+0x34/0x50 ret_from_fork_asm+0x1a/0x30 Kernel panic - not syncing: softlockup: hung tasks Between the bookworm and trixie kernels, the ACPI SCI handler was moved from a hardirq handler to a threaded handler by: 7a36b901a6eb ("ACPI: OSL: Use a threaded interrupt handler for SCI") To confirm this is the trigger, I reverted that commit on top of 6.12.41 and re-ran the same sysrq-trigger reproducer. The capture kernel then completes the crash dump without tripping the soft lockup watchdog. Happy to test patches or gather more data as this is reproducible consistently on our systems. This issue has been raised in the SONiC project at [2]. Context ------- - Kernel: 6.12.41+deb13-sonic-amd64 (Debian 6.12.41-1); - Last known good: Debian bookworm kernel (6.1.123), predates 7a36b901a6eb. - Default capture-kernel cmdline (from /etc/default/kdump-tools, KDUMP_CMDLINE_APPEND): irqpoll nr_cpus=1 nousb systemd.unit=kdump-tools.service ata_piix.prefer_ms_hyperv=0 panic=10 debug loglevel=4 hpet=disable pcie_port=compat pci=nommconf For the trace above, loglevel was raised from 4 to 7 and the following were added: debug=1 softlockup_all_cpu_backtrace=1 softlockup_panic=1 [0]: https://github.com/sonic-net [1]: https://github.com/sonic-net/sonic-linux-kernel/tree/master/patches-sonic [2]: https://github.com/sonic-net/sonic-linux-kernel/pull/580