svn commit: r355137 - head/sys/vm

[Gleb Smirnoff]

  Ryan,

On Wed, Nov 27, 2019 at 07:49:56PM +0000, Ryan Libby wrote:
R> Author: rlibby
R> Date: Wed Nov 27 19:49:55 2019
R> New Revision: 355137
R> URL: https://svnweb.freebsd.org/changeset/base/355137
R> 
R> Log:
R>   uma: trash memory when ctor/dtor supplied too
R>   
R>   On INVARIANTS kernels, UMA has a use-after-free detection mechanism.
R>   This mechanism previously required that all of the ctor/dtor/uminit/fini
R>   arguments to uma_zcreate() be NULL in order to function.  Now, it only
R>   requires that uminit and fini be NULL; now, the trash ctor and dtor will
R>   be called in addition to any supplied ctor or dtor.
R>   
R>   Also do a little refactoring for readability of the resulting logic.
R>   
R>   This enables use-after-free detection for more zones, and will allow for
R>   simplification of some callers that worked around the previous
R>   restriction (see kern_mbuf.c).
R>   
R>   Reviewed by:	jeff, markj
R>   Sponsored by:	Dell EMC Isilon
R>   Differential Revision:	https://reviews.freebsd.org/D20722

If I understand the change correct, now items from UMA_ZONE_NOFREE zones
will be trashed, too. That would undermine purpose of UMA_ZONE_NOFREE.
Of course the flag is a hack, but some systems rely on it working.

-- 
Gleb Smirnoff