4.19-stable review patch. If anyone has any objections, please let me know.
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From: Chen Yu yu.c.chen@intel.com
[ Upstream commit a0b0bad10587ae2948a7c36ca4ffc206007fbcf3 ]
When a CPU is about to be offlined, x86 validates that all active interrupts which are targeted to this CPU can be migrated to the remaining online CPUs. If not, the offline operation is aborted.
The validation uses irq_matrix_allocated() to retrieve the number of vectors which are allocated on the outgoing CPU. The returned number of allocated vectors includes also vectors which are associated to managed interrupts.
That's overaccounting because managed interrupts are:
- not migrated when the affinity mask of the interrupt targets only the outgoing CPU
- migrated to another CPU, but in that case the vector is already pre-allocated on the potential target CPUs and must not be taken into account.
As a consequence the check whether the remaining online CPUs have enough capacity for migrating the allocated vectors from the outgoing CPU might fail incorrectly.
Let irq_matrix_allocated() return only the number of allocated non-managed interrupts to make this validation check correct.
[ tglx: Amend changelog and fixup kernel-doc comment ]
Fixes: 2f75d9e1c905 ("genirq: Implement bitmap matrix allocator") Reported-by: Wendy Wang wendy.wang@intel.com Signed-off-by: Chen Yu yu.c.chen@intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Link: https://lore.kernel.org/r/20231020072522.557846-1-yu.c.chen@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/irq/matrix.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c index 8e586858bcf41..d25edbb87119f 100644 --- a/kernel/irq/matrix.c +++ b/kernel/irq/matrix.c @@ -466,16 +466,16 @@ unsigned int irq_matrix_reserved(struct irq_matrix *m) }
/** - * irq_matrix_allocated - Get the number of allocated irqs on the local cpu + * irq_matrix_allocated - Get the number of allocated non-managed irqs on the local CPU * @m: Pointer to the matrix to search * - * This returns number of allocated irqs + * This returns number of allocated non-managed interrupts. */ unsigned int irq_matrix_allocated(struct irq_matrix *m) { struct cpumap *cm = this_cpu_ptr(m->maps);
- return cm->allocated; + return cm->allocated - cm->managed_allocated; }
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS