K 10
svn:author
V 5
markj
K 8
svn:date
V 27
2018-10-22T16:16:42.629522Z
K 7
svn:log
V 585
Don't import 0 into vmem quantum caches.

vmem uses UMA cache zones to implement the quantum cache.  Since
uma_zalloc() returns 0 (NULL) to signal an allocation failure, UMA
should not be used to cache resource 0.  Fix this by ensuring that 0 is
never cached in UMA in the first place, and by modifying vmem_alloc()
to fall back to a search of the free lists if the cache is depleted,
rather than blocking in qc_import().

Reported by and discussed with:	Brett Gutstein <bgutstein@rice.edu>
Reviewed by:	alc
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D17483

END