Revision b90d72a6bfdb5e5c62cd223a8cdf4045bfbcb94d authored by Will Deacon on 12 January 2021, 22:18:55 UTC, committed by Catalin Marinas on 13 January 2021, 15:08:41 UTC
This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5. lockup_detector_init() makes heavy use of per-cpu variables and must be called with preemption disabled. Usually, it's handled early during boot in kernel_init_freeable(), before SMP has been initialised. Since we do not know whether or not our PMU interrupt can be signalled as an NMI until considerably later in the boot process, the Arm PMU driver attempts to re-initialise the lockup detector off the back of a device_initcall(). Unfortunately, this is called from preemptible context and results in the following splat: | BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 | caller is debug_smp_processor_id+0x20/0x2c | CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #276 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x3c0 | show_stack+0x20/0x6c | dump_stack+0x2f0/0x42c | check_preemption_disabled+0x1cc/0x1dc | debug_smp_processor_id+0x20/0x2c | hardlockup_detector_event_create+0x34/0x18c | hardlockup_detector_perf_init+0x2c/0x134 | watchdog_nmi_probe+0x18/0x24 | lockup_detector_init+0x44/0xa8 | armv8_pmu_driver_init+0x54/0x78 | do_one_initcall+0x184/0x43c | kernel_init_freeable+0x368/0x380 | kernel_init+0x1c/0x1cc | ret_from_fork+0x10/0x30 Rather than bodge this with raw_smp_processor_id() or randomly disabling preemption, simply revert the culprit for now until we figure out how to do this properly. Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Will Deacon <will@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Alexandru Elisei <alexandru.elisei@arm.com> Link: https://lore.kernel.org/r/20201221162249.3119-1-lecopzer.chen@mediatek.com Link: https://lore.kernel.org/r/20210112221855.10666-1-will@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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emu10k1_synth.h
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef __EMU10K1_SYNTH_H
#define __EMU10K1_SYNTH_H
/*
* Defines for the Emu10k1 WaveTable synth
*
* Copyright (C) 2000 Takashi Iwai <tiwai@suse.de>
*/
#include <sound/emu10k1.h>
#include <sound/emux_synth.h>
/* sequencer device id */
#define SNDRV_SEQ_DEV_ID_EMU10K1_SYNTH "emu10k1-synth"
/* argument for snd_seq_device_new */
struct snd_emu10k1_synth_arg {
struct snd_emu10k1 *hwptr; /* chip */
int index; /* sequencer client index */
int seq_ports; /* number of sequencer ports to be created */
int max_voices; /* maximum number of voices for wavetable */
};
#define EMU10K1_MAX_MEMSIZE (32 * 1024 * 1024) /* 32MB */
#endif
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