Page MenuHomeFreeBSD
Files F163351081

D27956.id81906.diff
No OneTemporary
Actions

D27956.id81906.diff
View Options

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -1275,6 +1275,8 @@
pd_entry_t newpde);
static void pmap_update_pde_invalidate(pmap_t, vm_offset_t va, pd_entry_t pde);
+static vm_page_t pmap_allocpte_nosleep(pmap_t pmap, vm_pindex_t ptepindex,
+ struct rwlock **lockp, vm_offset_t va);
static vm_page_t _pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex,
struct rwlock **lockp, vm_offset_t va);
static pd_entry_t *pmap_alloc_pde(pmap_t pmap, vm_offset_t va, vm_page_t *pdpgp,
@@ -4167,8 +4169,8 @@
pml5index = pmap_pml5e_index(va);
pml5 = &pmap->pm_pmltop[pml5index];
if ((*pml5 & PG_V) == 0) {
- if (_pmap_allocpte(pmap, pmap_pml5e_pindex(va), lockp, va) ==
- NULL)
+ if (pmap_allocpte_nosleep(pmap, pmap_pml5e_pindex(va), lockp,
+ va) == NULL)
return (NULL);
allocated = true;
} else {
@@ -4204,8 +4206,8 @@
if ((*pml4 & PG_V) == 0) {
/* Have to allocate a new pdp, recurse */
- if (_pmap_allocpte(pmap, pmap_pml4e_pindex(va), lockp, va) ==
- NULL) {
+ if (pmap_allocpte_nosleep(pmap, pmap_pml4e_pindex(va), lockp,
+ va) == NULL) {
if (pmap_is_la57(pmap))
pmap_allocpte_free_unref(pmap, va,
pmap_pml5e(pmap, va));
@@ -4231,12 +4233,11 @@
* This routine is called if the desired page table page does not exist.
*
* If page table page allocation fails, this routine may sleep before
- * returning NULL. It sleeps only if a lock pointer was given.
- *
- * Note: If a page allocation fails at page table level two, three, or four,
- * up to three pages may be held during the wait, only to be released
- * afterwards. This conservative approach is easily argued to avoid
- * race conditions.
+ * returning NULL. It sleeps only if a lock pointer was given. Sleep
+ * occurs right before returning from the top-level call, which is
+ * indicated by the first_level parameter. This way, we never drop
+ * pmap lock to sleep while a page table page has ref_count == 0,
+ * which prevents the page from being freed under us.
*
* The ptepindexes, i.e. page indices, of the page table pages encountered
* while translating virtual address va are defined as follows:
@@ -4271,8 +4272,8 @@
* since it is statically allocated by pmap_pinit() and not by _pmap_allocpte().
*/
static vm_page_t
-_pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, struct rwlock **lockp,
- vm_offset_t va __unused)
+pmap_allocpte_nosleep(pmap_t pmap, vm_pindex_t ptepindex, struct rwlock **lockp,
+ vm_offset_t va)
{
vm_pindex_t pml5index, pml4index;
pml5_entry_t *pml5, *pml5u;
@@ -4293,21 +4294,8 @@
* Allocate a page table page.
*/
if ((m = vm_page_alloc(NULL, ptepindex, VM_ALLOC_NOOBJ |
- VM_ALLOC_WIRED | VM_ALLOC_ZERO)) == NULL) {
- if (lockp != NULL) {
- RELEASE_PV_LIST_LOCK(lockp);
- PMAP_UNLOCK(pmap);
- PMAP_ASSERT_NOT_IN_DI();
- vm_wait(NULL);
- PMAP_LOCK(pmap);
- }
-
- /*
- * Indicate the need to retry. While waiting, the page table
- * page may have been allocated.
- */
+ VM_ALLOC_WIRED | VM_ALLOC_ZERO)) == NULL)
return (NULL);
- }
if ((m->flags & PG_ZERO) == 0)
pmap_zero_page(m);
@@ -4382,7 +4370,7 @@
}
if ((*pdp & PG_V) == 0) {
/* Have to allocate a new pd, recurse */
- if (_pmap_allocpte(pmap, pmap_pdpe_pindex(va),
+ if (pmap_allocpte_nosleep(pmap, pmap_pdpe_pindex(va),
lockp, va) == NULL) {
pmap_allocpte_free_unref(pmap, va,
pmap_pml4e(pmap, va));
@@ -4405,7 +4393,23 @@
}
pmap_resident_count_inc(pmap, 1);
+ return (m);
+}
+static vm_page_t
+_pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, struct rwlock **lockp,
+ vm_offset_t va)
+{
+ vm_page_t m;
+
+ m = pmap_allocpte_nosleep(pmap, ptepindex, lockp, va);
+ if (m == NULL && lockp != NULL) {
+ RELEASE_PV_LIST_LOCK(lockp);
+ PMAP_UNLOCK(pmap);
+ PMAP_ASSERT_NOT_IN_DI();
+ vm_wait(NULL);
+ PMAP_LOCK(pmap);
+ }
return (m);
}
@@ -7503,8 +7507,8 @@
pdpe = pmap_pdpe(dst_pmap, addr);
if (pdpe == NULL) {
if (_pmap_allocpte(dst_pmap,
- pmap_pml4e_pindex(addr), NULL, addr) ==
- NULL)
+ pmap_pml4e_pindex(addr), NULL,
+ addr) == NULL)
break;
pdpe = pmap_pdpe(dst_pmap, addr);
} else {
@@ -9363,6 +9367,8 @@
pa = 0;
val = 0;
pdpe = pmap_pdpe(pmap, addr);
+ if (pdpe == NULL)
+ goto out;
if ((*pdpe & PG_V) != 0) {
if ((*pdpe & PG_PS) != 0) {
pte = *pdpe;
@@ -9398,6 +9404,7 @@
(pte & (PG_MANAGED | PG_V)) == (PG_MANAGED | PG_V)) {
*pap = pa;
}
+out:
PMAP_UNLOCK(pmap);
return (val);
}

File Metadata

Mime Type
text/plain
Expires
Thu, Jul 23, 10:07 AM (8 m, 52 s)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
35398414
Default Alt Text
D27956.id81906.diff (4 KB)

Event Timeline