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9345005f4e
During heavy CPU-hotplug operations the following spurious kernel warnings can trigger: do_IRQ: No ... irq handler for vector (irq -1) [ See: https://bugzilla.kernel.org/show_bug.cgi?id=64831 ] When downing a cpu it is possible that there are unhandled irqs left in the APIC IRR register. The following code path shows how the problem can occur: 1. CPU 5 is to go down. 2. cpu_disable() on CPU 5 executes with interrupt flag cleared by local_irq_save() via stop_machine(). 3. IRQ 12 asserts on CPU 5, setting IRR but not ISR because interrupt flag is cleared (CPU unabled to handle the irq) 4. IRQs are migrated off of CPU 5, and the vectors' irqs are set to -1. 5. stop_machine() finishes cpu_disable() 6. cpu_die() for CPU 5 executes in normal context. 7. CPU 5 attempts to handle IRQ 12 because the IRR is set for IRQ 12. The code attempts to find the vector's IRQ and cannot because it has been set to -1. 8. do_IRQ() warning displays warning about CPU 5 IRQ 12. I added a debug printk to output which CPU & vector was retriggered and discovered that that we are getting bogus events. I see a 100% correlation between this debug printk in fixup_irqs() and the do_IRQ() warning. This patchset resolves this by adding definitions for VECTOR_UNDEFINED(-1) and VECTOR_RETRIGGERED(-2) and modifying the code to use them. Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=64831 Signed-off-by: Prarit Bhargava <prarit@redhat.com> Reviewed-by: Rui Wang <rui.y.wang@intel.com> Cc: Michel Lespinasse <walken@google.com> Cc: Seiji Aguchi <seiji.aguchi@hds.com> Cc: Yang Zhang <yang.z.zhang@Intel.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: janet.morgan@Intel.com Cc: tony.luck@Intel.com Cc: ruiv.wang@gmail.com Link: http://lkml.kernel.org/r/1388938252-16627-1-git-send-email-prarit@redhat.com [ Cleaned up the code a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> |
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