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Avoid a lock-order reversal and implement vm_object locking

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in vm_pageout_page_free().
This commit is contained in:
Alan Cox 2003-05-04 06:56:27 +00:00
parent df788a526f
commit c4a1d732a3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=114649
1 changed files with 8 additions and 8 deletions
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16
sys/vm/vm_pageout.c
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@ -613,25 +613,25 @@ vm_pageout_map_deactivate_pages(map, desired)
#endif /* !defined(NO_SWAPPING) */
/*
* Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore
* to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects
* which we know can be trivially freed.
* Warning! The page queue lock is released and reacquired.
*/
static void
vm_pageout_page_free(vm_page_t m)
{
vm_object_t object = m->object;
int type = object->type;
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
if (type == OBJT_SWAP || type == OBJT_DEFAULT)
vm_object_reference(object);
vm_page_busy(m);
vm_page_unlock_queues();
/*
* Avoid a lock order reversal. The page must be busy.
*/
VM_OBJECT_LOCK(object);
vm_page_lock_queues();
pmap_remove_all(m);
vm_page_free(m);
VM_OBJECT_UNLOCK(object);
cnt.v_dfree++;
if (type == OBJT_SWAP || type == OBJT_DEFAULT)
vm_object_deallocate(object);
}
/*