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Change get_pv_entry() such that the call to vm_page_alloc() specifies

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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@
This commit is contained in:
Alan Cox 2006-06-20 20:52:11 +00:00
parent 83ff9c1304
commit f05446648b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=159803
2 changed files with 30 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
sys/amd64/amd64/pmap.c
View File

@ -1664,7 +1664,7 @@ get_pv_entry(pmap_t pmap, int try)
static const struct timeval printinterval = { 60, 0 };
static struct timeval lastprint;
static vm_pindex_t colour;
int bit, field;
int bit, field, page_req;
pv_entry_t pv;
struct pv_chunk *pc;
vm_page_t m;
@ -1697,7 +1697,8 @@ get_pv_entry(pmap_t pmap, int try)
}
}
/* No free items, allocate another chunk */
m = vm_page_alloc(NULL, colour, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ);
page_req = try ? VM_ALLOC_NORMAL : VM_ALLOC_SYSTEM;
m = vm_page_alloc(NULL, colour, page_req | VM_ALLOC_NOOBJ);
if (m == NULL) {
if (try) {
pv_entry_count--;
@ -2335,6 +2336,7 @@ pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
vm_page_t m, mpte;
vm_pindex_t diff, psize;
VM_OBJECT_LOCK_ASSERT(m_start->object, MA_OWNED);
psize = atop(end - start);
mpte = NULL;
m = m_start;
@ -2376,7 +2378,6 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
(m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0,
("pmap_enter_quick_locked: managed mapping within the clean submap"));
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
/*
@ -2394,7 +2395,6 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
if (mpte && (mpte->pindex == ptepindex)) {
mpte->wire_count++;
} else {
retry:
/*
* Get the page directory entry
*/
@ -2412,18 +2412,8 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
} else {
mpte = _pmap_allocpte(pmap, ptepindex,
M_NOWAIT);
if (mpte == NULL) {
PMAP_UNLOCK(pmap);
vm_page_busy(m);
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(m->object);
VM_WAIT;
VM_OBJECT_LOCK(m->object);
vm_page_lock_queues();
vm_page_wakeup(m);
PMAP_LOCK(pmap);
goto retry;
}
if (mpte == NULL)
return (mpte);
}
}
} else {
@ -2446,12 +2436,16 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
}
/*
* Enter on the PV list if part of our managed memory. Note that we
* raise IPL while manipulating pv_table since pmap_enter can be
* called at interrupt time.
* Enter on the PV list if part of our managed memory.
*/
if ((m->flags & (PG_FICTITIOUS|PG_UNMANAGED)) == 0)
pmap_insert_entry(pmap, va, m);
if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0 &&
!pmap_try_insert_pv_entry(pmap, va, m)) {
if (mpte != NULL) {
pmap_unwire_pte_hold(pmap, va, mpte);
mpte = NULL;
}
return (mpte);
}
/*
* Increment counters

36
sys/i386/i386/pmap.c
View File

@ -1742,7 +1742,7 @@ get_pv_entry(pmap_t pmap, int try)
static const struct timeval printinterval = { 60, 0 };
static struct timeval lastprint;
static vm_pindex_t colour;
int bit, field;
int bit, field, page_req;
pv_entry_t pv;
struct pv_chunk *pc;
vm_page_t m;
@ -1777,7 +1777,8 @@ get_pv_entry(pmap_t pmap, int try)
}
}
pc = (struct pv_chunk *)pmap_ptelist_alloc(&pv_vafree);
m = vm_page_alloc(NULL, colour, VM_ALLOC_SYSTEM |
page_req = try ? VM_ALLOC_NORMAL : VM_ALLOC_SYSTEM;
m = vm_page_alloc(NULL, colour, page_req |
VM_ALLOC_NOOBJ | VM_ALLOC_WIRED);
if (m == NULL || pc == NULL) {
if (try) {
@ -2411,6 +2412,7 @@ pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
vm_page_t m, mpte;
vm_pindex_t diff, psize;
VM_OBJECT_LOCK_ASSERT(m_start->object, MA_OWNED);
psize = atop(end - start);
mpte = NULL;
m = m_start;
@ -2452,7 +2454,6 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
(m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0,
("pmap_enter_quick_locked: managed mapping within the clean submap"));
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
/*
@ -2470,7 +2471,6 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
if (mpte && (mpte->pindex == ptepindex)) {
mpte->wire_count++;
} else {
retry:
/*
* Get the page directory entry
*/
@ -2488,18 +2488,8 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
} else {
mpte = _pmap_allocpte(pmap, ptepindex,
M_NOWAIT);
if (mpte == NULL) {
PMAP_UNLOCK(pmap);
vm_page_busy(m);
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(m->object);
VM_WAIT;
VM_OBJECT_LOCK(m->object);
vm_page_lock_queues();
vm_page_wakeup(m);
PMAP_LOCK(pmap);
goto retry;
}
if (mpte == NULL)
return (mpte);
}
}
} else {
@ -2522,12 +2512,16 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
}
/*
* Enter on the PV list if part of our managed memory. Note that we
* raise IPL while manipulating pv_table since pmap_enter can be
* called at interrupt time.
* Enter on the PV list if part of our managed memory.
*/
if ((m->flags & (PG_FICTITIOUS|PG_UNMANAGED)) == 0)
pmap_insert_entry(pmap, va, m);
if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0 &&
!pmap_try_insert_pv_entry(pmap, va, m)) {
if (mpte != NULL) {
pmap_unwire_pte_hold(pmap, mpte);
mpte = NULL;
}
return (mpte);
}
/*
* Increment counters