K 10
svn:author
V 5
markj
K 8
svn:date
V 27
2019-02-03T18:38:58.938287Z
K 7
svn:log
V 564
Fix a race in vm_page_dequeue_deferred().

To detect the case where the page is already marked for a deferred
dequeue, we must read the "queue" and "aflags" fields in a
precise order.  Otherwise, a race with a concurrent
vm_page_dequeue_complete() could leave the page with PGA_DEQUEUE
set despite it already having been dequeued.  Fix the problem by
using vm_page_queue() to check the queue state, which correctly
handles the race.

Reviewed by:	kib
Tested by:	pho
MFC after:	3 days
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D19039

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