Update comments to routines in vm_page.c, most especially whether a
routine can block or not as part of a general effort to carefully
document blocking/non-blocking calls in the kernel.
This commit is contained in:
Matthew Dillon
parent
557d5a1caa
commit
9858fcda2e
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=42026
125
sys/vm/vm_page.c
125
sys/vm/vm_page.c
@ -34,7 +34,7 @@
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* SUCH DAMAGE.
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*
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* from: @(#)vm_page.c 7.4 (Berkeley) 5/7/91
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* $Id: vm_page.c,v 1.112 1998/10/28 13:41:43 dg Exp $
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* $Id: vm_page.c,v 1.113 1998/11/11 15:07:57 dg Exp $
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*/
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/*
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@ -352,6 +352,7 @@ vm_page_startup(starta, enda, vaddr)
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* Distributes the object/offset key pair among hash buckets.
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*
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* NOTE: This macro depends on vm_page_bucket_count being a power of 2.
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* This routine may not block.
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*/
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static __inline int
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vm_page_hash(object, pindex)
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@ -364,10 +365,15 @@ vm_page_hash(object, pindex)
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/*
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* vm_page_insert: [ internal use only ]
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*
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* Inserts the given mem entry into the object/object-page
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* table and object list.
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* Inserts the given mem entry into the object and object list.
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*
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* The pagetables are not updated but will presumably fault the page
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* in if necessary, or if a kernel page the caller will at some point
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* enter the page into the kernel's pmap. We are not allowed to block
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* here so we *can't* do this anyway.
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*
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* The object and page must be locked, and must be splhigh.
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* This routine may not block.
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*/
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void
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@ -425,6 +431,9 @@ vm_page_insert(m, object, pindex)
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* table and the object page list.
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*
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* The object and page must be locked, and at splhigh.
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* This routine may not block.
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*
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* I do not think the underlying pmap entry (if any) is removed here.
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*/
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void
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@ -490,6 +499,7 @@ vm_page_remove(m)
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* pair specified; if none is found, NULL is returned.
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*
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* The object must be locked. No side effects.
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* This routine may not block.
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*/
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vm_page_t
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@ -532,7 +542,11 @@ vm_page_lookup(object, pindex)
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* current object to the specified target object/offset.
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*
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* The object must be locked.
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* This routine may not block.
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*
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* Note: this routine will raise itself to splvm(), the caller need not.
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*/
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void
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vm_page_rename(m, new_object, new_pindex)
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register vm_page_t m;
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@ -548,8 +562,14 @@ vm_page_rename(m, new_object, new_pindex)
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}
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/*
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* vm_page_unqueue without any wakeup
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* vm_page_unqueue_nowakeup:
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*
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* vm_page_unqueue() without any wakeup
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*
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* This routine must be called at splhigh().
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* This routine may not block.
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*/
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void
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vm_page_unqueue_nowakeup(m)
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vm_page_t m;
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@ -570,8 +590,14 @@ vm_page_unqueue_nowakeup(m)
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}
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/*
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* vm_page_unqueue must be called at splhigh();
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* vm_page_unqueue:
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*
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* Remove a page from its queue.
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*
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* This routine must be called at splhigh().
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* This routine may not block.
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*/
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void
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vm_page_unqueue(m)
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vm_page_t m;
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@ -595,7 +621,12 @@ vm_page_unqueue(m)
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}
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/*
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* Find a page on the specified queue with color optimization.
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* vm_page_list_find:
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*
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* Find a page on the specified queue with color optimization.
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*
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* This routine must be called at splvm().
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* This routine may not block.
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*/
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vm_page_t
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vm_page_list_find(basequeue, index)
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@ -649,7 +680,12 @@ vm_page_list_find(basequeue, index)
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}
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/*
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* Find a page on the specified queue with color optimization.
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* vm_page_select:
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*
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* Find a page on the specified queue with color optimization.
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*
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* This routine must be called at splvm().
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* This routine may not block.
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*/
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vm_page_t
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vm_page_select(object, pindex, basequeue)
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@ -670,9 +706,14 @@ vm_page_select(object, pindex, basequeue)
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}
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/*
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* Find a page on the cache queue with color optimization. As pages
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* might be found, but not applicable, they are deactivated. This
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* keeps us from using potentially busy cached pages.
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* vm_page_select_cache:
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*
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* Find a page on the cache queue with color optimization. As pages
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* might be found, but not applicable, they are deactivated. This
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* keeps us from using potentially busy cached pages.
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*
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* This routine must be called at splvm().
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* This routine may not block.
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*/
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vm_page_t
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vm_page_select_cache(object, pindex)
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@ -700,8 +741,14 @@ vm_page_select_cache(object, pindex)
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}
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/*
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* Find a free or zero page, with specified preference.
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* vm_page_select_free:
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*
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* Find a free or zero page, with specified preference.
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*
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* This routine must be called at splvm().
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* This routine may not block.
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*/
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static vm_page_t
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vm_page_select_free(object, pindex, prefqueue)
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vm_object_t object;
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@ -805,6 +852,11 @@ vm_page_select_free(object, pindex, prefqueue)
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* VM_ALLOC_ZERO zero page
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*
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* Object must be locked.
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* This routine may not block.
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*
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* Additional special handling is required when called from an
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* interrupt (VM_ALLOC_INTERRUPT). We are not allowed to mess with
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* the page cache in this case.
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*/
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vm_page_t
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vm_page_alloc(object, pindex, page_req)
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@ -949,7 +1001,13 @@ vm_page_alloc(object, pindex, page_req)
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m->dirty = 0;
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m->queue = PQ_NONE;
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/* XXX before splx until vm_page_insert is safe */
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/*
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* vm_page_insert() is safe prior to the splx(). Note also that
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* inserting a page here does not insert it into the pmap (which
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* could cause us to block allocating memory). We cannot block
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* anywhere.
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*/
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vm_page_insert(m, object, pindex);
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/*
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@ -979,6 +1037,12 @@ vm_page_alloc(object, pindex, page_req)
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return (m);
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}
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/*
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* vm_wait: (also see VM_WAIT macro)
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*
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* Block until free pages are available for allocation
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*/
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void
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vm_wait()
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{
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@ -998,6 +1062,12 @@ vm_wait()
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splx(s);
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}
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/*
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* vm_page_sleep:
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*
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* Block until page is no longer busy.
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*/
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int
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vm_page_sleep(vm_page_t m, char *msg, char *busy) {
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int slept = 0;
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@ -1020,6 +1090,7 @@ vm_page_sleep(vm_page_t m, char *msg, char *busy) {
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* Put the specified page on the active list (if appropriate).
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*
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* The page queues must be locked.
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* This routine may not block.
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*/
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void
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vm_page_activate(m)
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@ -1051,7 +1122,9 @@ vm_page_activate(m)
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}
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/*
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* helper routine for vm_page_free and vm_page_free_zero
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* helper routine for vm_page_free and vm_page_free_zero.
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*
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* This routine may not block.
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*/
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static int
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vm_page_freechk_and_unqueue(m)
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@ -1118,7 +1191,9 @@ vm_page_freechk_and_unqueue(m)
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}
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/*
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* helper routine for vm_page_free and vm_page_free_zero
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* helper routine for vm_page_free and vm_page_free_zero.
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*
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* This routine may not block.
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*/
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static __inline void
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vm_page_free_wakeup()
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@ -1151,6 +1226,7 @@ vm_page_free_wakeup()
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* disassociating it with any VM object.
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*
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* Object and page must be locked prior to entry.
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* This routine may not block.
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*/
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void
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vm_page_free(m)
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@ -1223,6 +1299,7 @@ vm_page_free_zero(m)
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* as necessary.
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*
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* The page queues must be locked.
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* This routine may not block.
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*/
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void
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vm_page_wire(m)
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@ -1250,6 +1327,7 @@ vm_page_wire(m)
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* enabling it to be paged again.
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*
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* The page queues must be locked.
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* This routine may not block.
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*/
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void
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vm_page_unwire(m, activate)
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@ -1289,6 +1367,8 @@ vm_page_unwire(m, activate)
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/*
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* Move the specified page to the inactive queue.
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*
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* This routine may not block.
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*/
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void
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vm_page_deactivate(m)
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@ -1318,7 +1398,8 @@ vm_page_deactivate(m)
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/*
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* vm_page_cache
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*
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* Put the specified page onto the page cache queue (if appropriate).
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* Put the specified page onto the page cache queue (if appropriate).
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* This routine may not block.
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*/
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void
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vm_page_cache(m)
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@ -1356,6 +1437,8 @@ vm_page_cache(m)
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* Grab a page, waiting until we are waken up due to the page
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* changing state. We keep on waiting, if the page continues
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* to be in the object. If the page doesn't exist, allocate it.
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*
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* This routine may block.
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*/
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vm_page_t
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vm_page_grab(object, pindex, allocflags)
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@ -1403,7 +1486,7 @@ vm_page_grab(object, pindex, allocflags)
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/*
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* mapping function for valid bits or for dirty bits in
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* a page
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* a page. May not block.
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*/
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__inline int
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vm_page_bits(int base, int size)
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@ -1425,7 +1508,7 @@ vm_page_bits(int base, int size)
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}
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/*
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* set a page valid and clean
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* set a page valid and clean. May not block.
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*/
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void
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vm_page_set_validclean(m, base, size)
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@ -1441,7 +1524,7 @@ vm_page_set_validclean(m, base, size)
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}
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/*
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* set a page (partially) invalid
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* set a page (partially) invalid. May not block.
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*/
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void
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vm_page_set_invalid(m, base, size)
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@ -1458,7 +1541,7 @@ vm_page_set_invalid(m, base, size)
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}
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/*
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* is (partial) page valid?
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* is (partial) page valid? May not block.
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*/
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int
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vm_page_is_valid(m, base, size)
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@ -1474,6 +1557,10 @@ vm_page_is_valid(m, base, size)
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return 0;
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}
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/*
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* update dirty bits from pmap/mmu. May not block.
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*/
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void
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vm_page_test_dirty(m)
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vm_page_t m;
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