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(fault 9/9) Move zero fill into a dedicated function to make the object lock

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state more clear.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D23326
This commit is contained in:
jeff 2020-01-23 05:23:37 +00:00
parent d14b7761cb
commit e386d832f5
1 changed files with 38 additions and 33 deletions
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71
sys/vm/vm_fault.c
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@ -960,35 +960,8 @@ vm_fault_next(struct faultstate *fs)
*/
VM_OBJECT_ASSERT_WLOCKED(fs->object);
next_object = fs->object->backing_object;
if (next_object == NULL) {
/*
* If there's no object left, fill the page in the top
* object with zeros.
*/
VM_OBJECT_WUNLOCK(fs->object);
if (fs->object != fs->first_object) {
vm_object_pip_wakeup(fs->object);
fs->object = fs->first_object;
fs->pindex = fs->first_pindex;
}
MPASS(fs->first_m != NULL);
MPASS(fs->m == NULL);
fs->m = fs->first_m;
fs->first_m = NULL;
/*
* Zero the page if necessary and mark it valid.
*/
if ((fs->m->flags & PG_ZERO) == 0) {
pmap_zero_page(fs->m);
} else {
VM_CNT_INC(v_ozfod);
}
VM_CNT_INC(v_zfod);
vm_page_valid(fs->m);
if (next_object == NULL)
return (false);
}
MPASS(fs->first_m != NULL);
KASSERT(fs->object != next_object, ("object loop %p", next_object));
VM_OBJECT_WLOCK(next_object);
@ -1002,6 +975,36 @@ vm_fault_next(struct faultstate *fs)
return (true);
}
static void
vm_fault_zerofill(struct faultstate *fs)
{
/*
* If there's no object left, fill the page in the top
* object with zeros.
*/
if (fs->object != fs->first_object) {
vm_object_pip_wakeup(fs->object);
fs->object = fs->first_object;
fs->pindex = fs->first_pindex;
}
MPASS(fs->first_m != NULL);
MPASS(fs->m == NULL);
fs->m = fs->first_m;
fs->first_m = NULL;
/*
* Zero the page if necessary and mark it valid.
*/
if ((fs->m->flags & PG_ZERO) == 0) {
pmap_zero_page(fs->m);
} else {
VM_CNT_INC(v_ozfod);
}
VM_CNT_INC(v_zfod);
vm_page_valid(fs->m);
}
/*
* Allocate a page directly or via the object populate method.
*/
@ -1407,11 +1410,13 @@ RetryFault:
* traverse into a backing object or zero fill if none is
* found.
*/
if (!vm_fault_next(&fs)) {
/* Don't try to prefault neighboring pages. */
faultcount = 1;
break; /* break to PAGE HAS BEEN FOUND. */
}
if (vm_fault_next(&fs))
continue;
VM_OBJECT_WUNLOCK(fs.object);
vm_fault_zerofill(&fs);
/* Don't try to prefault neighboring pages. */
faultcount = 1;
break; /* break to PAGE HAS BEEN FOUND. */
}
/*