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Gavin ShanYuryNorov
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cpumask: Fix crash on updating CPU enabled mask
The CPU enabled mask instead of the CPU possible mask should be used by set_cpu_enabled(). Otherwise, we run into crash due to write to the read-only CPU possible mask when vCPU is hot added on ARM64. (qemu) device_add host-arm-cpu,id=cpu1,socket-id=1 Unable to handle kernel write to read-only memory at virtual address ffff800080fa7190 : Call trace: register_cpu+0x1a4/0x2e8 arch_register_cpu+0x84/0xd8 acpi_processor_add+0x480/0x5b0 acpi_bus_attach+0x1c4/0x300 acpi_dev_for_one_check+0x3c/0x50 device_for_each_child+0x68/0xc8 acpi_dev_for_each_child+0x48/0x80 acpi_bus_attach+0x84/0x300 acpi_bus_scan+0x74/0x220 acpi_scan_rescan_bus+0x54/0x88 acpi_device_hotplug+0x208/0x478 acpi_hotplug_work_fn+0x2c/0x50 process_one_work+0x15c/0x3c0 worker_thread+0x2ec/0x400 kthread+0x120/0x130 ret_from_fork+0x10/0x20 Fix it by passing the CPU enabled mask instead of the CPU possible mask to set_cpu_enabled(). Fixes: 51c4767 ("Merge tag 'bitmap-6.11-rc1' of https://github.com:/norov/linux") Signed-off-by: Gavin Shan <gshan@redhat.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Yury Norov <yury.norov@gmail.com>
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include/linux/cpumask.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1037,7 +1037,7 @@ void init_cpu_online(const struct cpumask *src);
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assign_bit(cpumask_check(cpu), cpumask_bits(mask), (val))
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#define set_cpu_possible(cpu, possible) assign_cpu((cpu), &__cpu_possible_mask, (possible))
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#define set_cpu_enabled(cpu, enabled) assign_cpu((cpu), &__cpu_possible_mask, (enabled))
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#define set_cpu_enabled(cpu, enabled) assign_cpu((cpu), &__cpu_enabled_mask, (enabled))
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#define set_cpu_present(cpu, present) assign_cpu((cpu), &__cpu_present_mask, (present))
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#define set_cpu_active(cpu, active) assign_cpu((cpu), &__cpu_active_mask, (active))
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#define set_cpu_dying(cpu, dying) assign_cpu((cpu), &__cpu_dying_mask, (dying))

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