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Re-count available PV entries after reclaiming a PV chunk.

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The call to reclaim_pv_chunk() in reserve_pv_entries() may free a
PV chunk with free entries belonging to the current pmap.  In this
case we must account for the free entries that were reclaimed, or
reserve_pv_entries() may return without having reserved the requested
number of entries.

Reviewed by:	alc, kib
Tested by:	pho (previous version)
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D15911
This commit is contained in:
Mark Johnston 2018-06-23 10:41:52 +00:00
parent 63b5557b2f
commit a8be239d69
2 changed files with 24 additions and 4 deletions
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14
sys/amd64/amd64/pmap.c
View file

@ -3539,8 +3539,9 @@ reserve_pv_entries(pmap_t pmap, int needed, struct rwlock **lockp)
{
struct pch new_tail;
struct pv_chunk *pc;
int avail, free;
vm_page_t m;
int avail, free;
bool reclaimed;
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
KASSERT(lockp != NULL, ("reserve_pv_entries: lockp is NULL"));
@ -3568,13 +3569,14 @@ retry:
if (avail >= needed)
break;
}
for (; avail < needed; avail += _NPCPV) {
for (reclaimed = false; avail < needed; avail += _NPCPV) {
m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ |
VM_ALLOC_WIRED);
if (m == NULL) {
m = reclaim_pv_chunk(pmap, lockp);
if (m == NULL)
goto retry;
reclaimed = true;
}
PV_STAT(atomic_add_int(&pc_chunk_count, 1));
PV_STAT(atomic_add_int(&pc_chunk_allocs, 1));
@ -3587,6 +3589,14 @@ retry:
TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
TAILQ_INSERT_TAIL(&new_tail, pc, pc_lru);
PV_STAT(atomic_add_int(&pv_entry_spare, _NPCPV));
/*
* The reclaim might have freed a chunk from the current pmap.
* If that chunk contained available entries, we need to
* re-count the number of available entries.
*/
if (reclaimed)
goto retry;
}
if (!TAILQ_EMPTY(&new_tail)) {
mtx_lock(&pv_chunks_mutex);

14
sys/arm64/arm64/pmap.c
View file

@ -2083,8 +2083,9 @@ reserve_pv_entries(pmap_t pmap, int needed, struct rwlock **lockp)
{
struct pch new_tail;
struct pv_chunk *pc;
int avail, free;
vm_page_t m;
int avail, free;
bool reclaimed;
PMAP_LOCK_ASSERT(pmap, MA_OWNED);
KASSERT(lockp != NULL, ("reserve_pv_entries: lockp is NULL"));
@ -2107,13 +2108,14 @@ retry:
if (avail >= needed)
break;
}
for (; avail < needed; avail += _NPCPV) {
for (reclaimed = false; avail < needed; avail += _NPCPV) {
m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ |
VM_ALLOC_WIRED);
if (m == NULL) {
m = reclaim_pv_chunk(pmap, lockp);
if (m == NULL)
goto retry;
reclaimed = true;
}
PV_STAT(atomic_add_int(&pc_chunk_count, 1));
PV_STAT(atomic_add_int(&pc_chunk_allocs, 1));
@ -2126,6 +2128,14 @@ retry:
TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
TAILQ_INSERT_TAIL(&new_tail, pc, pc_lru);
PV_STAT(atomic_add_int(&pv_entry_spare, _NPCPV));
/*
* The reclaim might have freed a chunk from the current pmap.
* If that chunk contained available entries, we need to
* re-count the number of available entries.
*/
if (reclaimed)
goto retry;
}
if (!TAILQ_EMPTY(&new_tail)) {
mtx_lock(&pv_chunks_mutex);