vm_pageout_flush() might cache the pages that finished write to the

backing storage. Such pages might be then reused, racing with the
assert in vm_object_page_collect_flush() that verified that dirty
pages from the run (most likely, pages with VM_PAGER_AGAIN status) are
write-protected still. In fact, the page indexes for the pages that
were removed from the object page list should be ignored by
vm_object_page_clean().

Return the length of successfully written run from vm_pageout_flush(),
that is, the count of pages between requested page and first page
after requested with status VM_PAGER_AGAIN. Supply the requested page
index in the array to vm_pageout_flush(). Use the returned run length
to forward the index of next page to clean in vm_object_page_clean().

Reported by:	avg
Reviewed by:	alc
MFC after:	1 week

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/vm/vm_contig.c b/sys/vm/vm_contig.c
index c0a9fcd..3341634 100644
--- a/sys/vm/vm_contig.c
+++ b/sys/vm/vm_contig.c
@@ -140,7 +140,7 @@ vm_contig_launder_page(vm_page_t m, vm_page_t *next)
 			   object->type == OBJT_DEFAULT) {
 			vm_page_unlock_queues();
 			m_tmp = m;
-			vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC);
+			vm_pageout_flush(&m_tmp, 1, VM_PAGER_PUT_SYNC, 0, NULL);
 			VM_OBJECT_UNLOCK(object);
 			vm_page_lock_queues();
 			return (0);