Acquire the vm object lock before rather than after calling vm_page_sleep_if_busy().  (The motivation being to transition synchronization of the vm_page's PG_BUSY flag from the global page queues lock to the per-object lock.)
Acquire the vm object lock before rather than after calling
vm_page_sleep_if_busy().  (The motivation being to transition
synchronization of the vm_page's PG_BUSY flag from the global page queues
lock to the per-object lock.)

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