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author | kib <kib@FreeBSD.org> | 2015-11-02 13:14:27 +0000 |
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committer | kib <kib@FreeBSD.org> | 2015-11-02 13:14:27 +0000 |
commit | 1cfef4015ed1c4b9f7101ea6be8b785dd4b11f0d (patch) | |
tree | 2764e6d02df371036e65361126994599e31ac738 | |
parent | 53802741e62fe78e1a0e452b31642498a27474bb (diff) | |
download | FreeBSD-src-1cfef4015ed1c4b9f7101ea6be8b785dd4b11f0d.zip FreeBSD-src-1cfef4015ed1c4b9f7101ea6be8b785dd4b11f0d.tar.gz |
MFC r289496:
Modify the 'unchanged' calculation bu dereferencing the marker tailq
pointers, which is known to belong to the queue.
-rw-r--r-- | sys/vm/vm_pageout.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c index ed80b1b..2cc738d 100644 --- a/sys/vm/vm_pageout.c +++ b/sys/vm/vm_pageout.c @@ -286,11 +286,21 @@ vm_pageout_fallback_object_lock(vm_page_t m, vm_page_t *next) vm_page_lock(m); vm_pagequeue_lock(pq); - /* Page queue might have changed. */ + /* + * The page's object might have changed, and/or the page might + * have moved from its original position in the queue. If the + * page's object has changed, then the caller should abandon + * processing the page because the wrong object lock was + * acquired. Use the marker's plinks.q, not the page's, to + * determine if the page has been moved. The state of the + * page's plinks.q can be indeterminate; whereas, the marker's + * plinks.q must be valid. + */ *next = TAILQ_NEXT(&marker, plinks.q); - unchanged = (m->queue == queue && - m->object == object && - &marker == TAILQ_NEXT(m, plinks.q)); + unchanged = m->object == object && + m == TAILQ_PREV(&marker, pglist, plinks.q); + KASSERT(!unchanged || m->queue == queue, + ("page %p queue %d %d", m, queue, m->queue)); TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); return (unchanged); } @@ -327,7 +337,9 @@ vm_pageout_page_lock(vm_page_t m, vm_page_t *next) /* Page queue might have changed. */ *next = TAILQ_NEXT(&marker, plinks.q); - unchanged = (m->queue == queue && &marker == TAILQ_NEXT(m, plinks.q)); + unchanged = m == TAILQ_PREV(&marker, pglist, plinks.q); + KASSERT(!unchanged || m->queue == queue, + ("page %p queue %d %d", m, queue, m->queue)); TAILQ_REMOVE(&pq->pq_pl, &marker, plinks.q); return (unchanged); } |