K 10
svn:author
V 5
markj
K 8
svn:date
V 27
2020-02-17T15:10:41.418477Z
K 7
svn:log
V 587
Fix a swap block allocation race.

putpages' allocation of swap blocks is done under the global sw_dev
lock.  Previously it would drop that lock before inserting the allocated
blocks into the object's trie, creating a window in which swap blocks
are allocated but are not visible to swapoff.  This can cause
swp_pager_strategy() to fail and panic the system.

Fix the problem bluntly, by allocating swap blocks under the object
lock.

Reviewed by:	jeff, kib
Tested by:	pho
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23665

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