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commit52d6b926aaupstream. There is a race when taking a CPU offline. Current code looks like this: native_cpu_disable() { ... apic_soft_disable(); /* * Any existing set bits for pending interrupt to * this CPU are preserved and will be sent via IPI * to another CPU by fixup_irqs(). */ cpu_disable_common(); { .... /* * Race window happens here. Once local APIC has been * disabled any new interrupts from the device to * the old CPU are lost */ fixup_irqs(); // Too late to capture anything in IRR. ... } } The fix is to disable the APIC *after* cpu_disable_common(). Testing was done with a USB NIC that provided a source of frequent interrupts. A script migrated interrupts to a specific CPU and then took that CPU offline. Fixes:60dcaad573("x86/hotplug: Silence APIC and NMI when CPU is dead") Reported-by: Evan Green <evgreen@chromium.org> Signed-off-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mathias Nyman <mathias.nyman@linux.intel.com> Tested-by: Evan Green <evgreen@chromium.org> Reviewed-by: Evan Green <evgreen@chromium.org> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/lkml/875zdarr4h.fsf@nanos.tec.linutronix.de/ Link: https://lore.kernel.org/r/1598501530-45821-1-git-send-email-ashok.raj@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.