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Cache the next queue element when traversing a page queue.

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When QUEUE_MACRO_DEBUG_TRASH is configured, removing a queue element
invalidates its queue linkage pointers.  vm_pageout_collect_batch()
was relying on these pointers remaining valid after a removal, so
modify it to fetch the next queued page before dequeuing the current
page.

Submitted by:	Don Morris <dgmorris@earthlink.net>
Reviewed by:	cem, vangyzen
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D20842
This commit is contained in:
Mark Johnston 2019-07-03 18:46:39 +00:00
parent 55c94d640f
commit d70f0ab38d
1 changed files with 3 additions and 2 deletions
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5
sys/vm/vm_pageout.c
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@ -266,7 +266,7 @@ static __always_inline void
vm_pageout_collect_batch(struct scan_state *ss, const bool dequeue)
{
struct vm_pagequeue *pq;
vm_page_t m, marker;
vm_page_t m, marker, n;
marker = ss->marker;
pq = ss->pq;
@ -277,7 +277,8 @@ vm_pageout_collect_batch(struct scan_state *ss, const bool dequeue)
vm_pagequeue_lock(pq);
for (m = TAILQ_NEXT(marker, plinks.q); m != NULL &&
ss->scanned < ss->maxscan && ss->bq.bq_cnt < VM_BATCHQUEUE_SIZE;
m = TAILQ_NEXT(m, plinks.q), ss->scanned++) {
m = n, ss->scanned++) {
n = TAILQ_NEXT(m, plinks.q);
if ((m->flags & PG_MARKER) == 0) {
KASSERT((m->aflags & PGA_ENQUEUED) != 0,
("page %p not enqueued", m));