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Date: Tue, 12 Jan 2021 13:59:48 +0000 From: Mark Rutland <mark.rutland@....com> To: linux-kernel@...r.kernel.org Cc: mark.rutland@....com, maz@...nel.org, paulmck@...nel.org, peterz@...radead.org, tglx@...utronix.de Subject: [PATCH 0/2] irq: detect slow IRQ handlers Hi, While fuzzing arm64 with Syzkaller (under QEMU+KVM) over a number of releases, I've occasionally seen some ridiculously long stalls (20+ seconds), where it appears that a CPU is stuck in a hard IRQ context. As this gets detected after the CPU returns to the interrupted context, it's difficult to identify where exactly the stall is coming from. These patches are intended to help tracking this down, with a WARN() if an IRQ handler takes longer than a given timout (1 second by default), logging the specific IRQ and handler function. While it's possible to achieve similar with tracing, it's harder to integrate that into an automated fuzzing setup. I've been running this for a short while, and haven't yet seen any of the stalls with this applied, but I've tested with smaller timeout periods in the 1 millisecond range by overloading the host, so I'm confident that the check works. Thanks, Mark. Mark Rutland (2): irq: abstract irqaction handler invocation irq: detect long-running IRQ handlers kernel/irq/chip.c | 15 +++---------- kernel/irq/handle.c | 4 +--- kernel/irq/internals.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++ lib/Kconfig.debug | 15 +++++++++++++ 4 files changed, 76 insertions(+), 15 deletions(-) -- 2.11.0
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