13b4d64335
VM_ALLOC_NORMAL instead of VM_ALLOC_SYSTEM when try is TRUE. In other words, when get_pv_entry() is permitted to fail, it no longer tries as hard to allocate a page. Change pmap_enter_quick_locked() to fail rather than wait if it is unable to allocate a page table page. This prevents a race between pmap_enter_object() and the page daemon. Specifically, an inactive page that is a successor to the page that was given to pmap_enter_quick_locked() might become a cache page while pmap_enter_quick_locked() waits and later pmap_enter_object() maps the cache page violating the invariant that cache pages are never mapped. Similarly, change pmap_enter_quick_locked() to call pmap_try_insert_pv_entry() rather than pmap_insert_entry(). Generally speaking, pmap_enter_quick_locked() is used to create speculative mappings. So, it should not try hard to allocate memory if free memory is scarce. Add an assertion that the object containing m_start is locked in pmap_enter_object(). Remove a similar assertion from pmap_enter_quick_locked() because that function no longer accesses the containing object. Remove a stale comment. Reviewed by: ups@ |
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