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Relax the object locking in vm_fault_prefault(). A read lock suffices.

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Reviewed by:	attilio
Sponsored by:	EMC / Isilon Storage Division
This commit is contained in:
Alan Cox 2013-05-17 19:02:36 +00:00
parent 658f180b3b
commit c141ae7f49
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=250748
1 changed files with 5 additions and 5 deletions
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10
sys/vm/vm_fault.c
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@ -1044,28 +1044,28 @@ vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry)
pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
lobject = object;
VM_OBJECT_WLOCK(lobject);
VM_OBJECT_RLOCK(lobject);
while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
lobject->type == OBJT_DEFAULT &&
(backing_object = lobject->backing_object) != NULL) {
KASSERT((lobject->backing_object_offset & PAGE_MASK) ==
0, ("vm_fault_prefault: unaligned object offset"));
pindex += lobject->backing_object_offset >> PAGE_SHIFT;
VM_OBJECT_WLOCK(backing_object);
VM_OBJECT_WUNLOCK(lobject);
VM_OBJECT_RLOCK(backing_object);
VM_OBJECT_RUNLOCK(lobject);
lobject = backing_object;
}
/*
* give-up when a page is not in memory
*/
if (m == NULL) {
VM_OBJECT_WUNLOCK(lobject);
VM_OBJECT_RUNLOCK(lobject);
break;
}
if (m->valid == VM_PAGE_BITS_ALL &&
(m->flags & PG_FICTITIOUS) == 0)
pmap_enter_quick(pmap, addr, m, entry->protection);
VM_OBJECT_WUNLOCK(lobject);
VM_OBJECT_RUNLOCK(lobject);
}
}