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Remove a couple of lingering usages of the page lock.

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Update vm_page_scan_contig() and vm_page_reclaim_run() to stop using
vm_page_change_lock().  It has no use after r356157.  Remove
vm_page_change_lock() now that it has no users.

Remove an unncessary check for wirings in vm_page_scan_contig(), which
was previously checking twice.  The check is racy until
vm_page_reclaim_run() ensures that the page is unmapped, so one check is
sufficient.

Reviewed by:	jeff, kib (previous versions)
Tested by:	pho (previous version)
Differential Revision:	https://reviews.freebsd.org/D23279
This commit is contained in:
Mark Johnston 2020-02-01 18:23:51 +00:00
parent f591c3c847
commit f0a273c00f
2 changed files with 16 additions and 64 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
sys/vm/vm_page.c
View File

@ -1155,23 +1155,6 @@ vm_page_xunbusy_hard_unchecked(vm_page_t m)
vm_page_xunbusy_hard_tail(m);
}
/*
* Avoid releasing and reacquiring the same page lock.
*/
void
vm_page_change_lock(vm_page_t m, struct mtx **mtx)
{
struct mtx *mtx1;
mtx1 = vm_page_lockptr(m);
if (*mtx == mtx1)
return;
if (*mtx != NULL)
mtx_unlock(*mtx);
*mtx = mtx1;
mtx_lock(mtx1);
}
/*
* vm_page_unhold_pages:
*
@ -2444,7 +2427,6 @@ vm_page_t
vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
u_long alignment, vm_paddr_t boundary, int options)
{
struct mtx *m_mtx;
vm_object_t object;
vm_paddr_t pa;
vm_page_t m, m_run;
@ -2458,7 +2440,6 @@ vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
m_run = NULL;
run_len = 0;
m_mtx = NULL;
for (m = m_start; m < m_end && run_len < npages; m += m_inc) {
KASSERT((m->flags & PG_MARKER) == 0,
("page %p is PG_MARKER", m));
@ -2489,9 +2470,8 @@ vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
} else
KASSERT(m_run != NULL, ("m_run == NULL"));
vm_page_change_lock(m, &m_mtx);
m_inc = 1;
retry:
m_inc = 1;
if (vm_page_wired(m))
run_ext = 0;
#if VM_NRESERVLEVEL > 0
@ -2504,23 +2484,17 @@ vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
pa);
}
#endif
else if ((object = m->object) != NULL) {
else if ((object =
(vm_object_t)atomic_load_ptr(&m->object)) != NULL) {
/*
* The page is considered eligible for relocation if
* and only if it could be laundered or reclaimed by
* the page daemon.
*/
if (!VM_OBJECT_TRYRLOCK(object)) {
mtx_unlock(m_mtx);
VM_OBJECT_RLOCK(object);
mtx_lock(m_mtx);
if (m->object != object) {
/*
* The page may have been freed.
*/
VM_OBJECT_RUNLOCK(object);
goto retry;
}
VM_OBJECT_RLOCK(object);
if (object != m->object) {
VM_OBJECT_RUNLOCK(object);
goto retry;
}
/* Don't care: PG_NODUMP, PG_ZERO. */
if (object->type != OBJT_DEFAULT &&
@ -2537,8 +2511,7 @@ vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
vm_reserv_size(level)) - pa);
#endif
} else if (object->memattr == VM_MEMATTR_DEFAULT &&
vm_page_queue(m) != PQ_NONE && !vm_page_busied(m) &&
!vm_page_wired(m)) {
vm_page_queue(m) != PQ_NONE && !vm_page_busied(m)) {
/*
* The page is allocated but eligible for
* relocation. Extend the current run by one
@ -2605,8 +2578,6 @@ vm_page_scan_contig(u_long npages, vm_page_t m_start, vm_page_t m_end,
}
}
}
if (m_mtx != NULL)
mtx_unlock(m_mtx);
if (run_len >= npages)
return (m_run);
return (NULL);
@ -2634,7 +2605,6 @@ vm_page_reclaim_run(int req_class, int domain, u_long npages, vm_page_t m_run,
vm_paddr_t high)
{
struct vm_domain *vmd;
struct mtx *m_mtx;
struct spglist free;
vm_object_t object;
vm_paddr_t pa;
@ -2647,42 +2617,28 @@ vm_page_reclaim_run(int req_class, int domain, u_long npages, vm_page_t m_run,
error = 0;
m = m_run;
m_end = m_run + npages;
m_mtx = NULL;
for (; error == 0 && m < m_end; m++) {
KASSERT((m->flags & (PG_FICTITIOUS | PG_MARKER)) == 0,
("page %p is PG_FICTITIOUS or PG_MARKER", m));
/*
* Avoid releasing and reacquiring the same page lock.
*/
vm_page_change_lock(m, &m_mtx);
retry:
/*
* Racily check for wirings. Races are handled below.
* Racily check for wirings. Races are handled once the object
* lock is held and the page is unmapped.
*/
if (vm_page_wired(m))
error = EBUSY;
else if ((object = m->object) != NULL) {
else if ((object =
(vm_object_t)atomic_load_ptr(&m->object)) != NULL) {
/*
* The page is relocated if and only if it could be
* laundered or reclaimed by the page daemon.
*/
if (!VM_OBJECT_TRYWLOCK(object)) {
mtx_unlock(m_mtx);
VM_OBJECT_WLOCK(object);
mtx_lock(m_mtx);
if (m->object != object) {
/*
* The page may have been freed.
*/
VM_OBJECT_WUNLOCK(object);
goto retry;
}
}
VM_OBJECT_WLOCK(object);
/* Don't care: PG_NODUMP, PG_ZERO. */
if (object->type != OBJT_DEFAULT &&
if (m->object != object ||
(object->type != OBJT_DEFAULT &&
object->type != OBJT_SWAP &&
object->type != OBJT_VNODE)
object->type != OBJT_VNODE))
error = EINVAL;
else if (object->memattr != VM_MEMATTR_DEFAULT)
error = EINVAL;
@ -2781,7 +2737,6 @@ vm_page_reclaim_run(int req_class, int domain, u_long npages, vm_page_t m_run,
* The new page must be deactivated
* before the object is unlocked.
*/
vm_page_change_lock(m_new, &m_mtx);
vm_page_deactivate(m_new);
} else {
m->flags &= ~PG_ZERO;
@ -2821,8 +2776,6 @@ vm_page_reclaim_run(int req_class, int domain, u_long npages, vm_page_t m_run,
error = EINVAL;
}
}
if (m_mtx != NULL)
mtx_unlock(m_mtx);
if ((m = SLIST_FIRST(&free)) != NULL) {
int cnt;

1
sys/vm/vm_page.h
View File

@ -609,7 +609,6 @@ vm_page_t vm_page_alloc_freelist(int, int);
vm_page_t vm_page_alloc_freelist_domain(int, int, int);
void vm_page_bits_set(vm_page_t m, vm_page_bits_t *bits, vm_page_bits_t set);
bool vm_page_blacklist_add(vm_paddr_t pa, bool verbose);
void vm_page_change_lock(vm_page_t m, struct mtx **mtx);
vm_page_t vm_page_grab (vm_object_t, vm_pindex_t, int);
int vm_page_grab_pages(vm_object_t object, vm_pindex_t pindex, int allocflags,
vm_page_t *ma, int count);