tegge a814ebd3df Revert change in revision 1.53 and add a small comment to protect
the revived code.

vm pages newly allocated are marked busy (PG_BUSY), thus calling
vm_page_delete before the pages has been freed or unbusied will
cause a deadlock since vm_page_object_page_remove will wait for the
busy flag to be cleared.  This can be triggered by calling malloc
with size > PAGE_SIZE and the M_NOWAIT flag on systems low on
physical free memory.

A kernel module that reproduces the problem, written by Logan Gabriel
<logan@mail.2cactus.com>, can be found in the freebsd-hackers mail
archive (12 Apr 2001).  The problem was recently noticed again by
Archie Cobbs <archie@dellroad.org>.

Reviewed by:	dillon
2002-03-09 16:24:27 +00:00
..
2002-02-07 20:58:47 +00:00
2002-02-26 01:01:37 +00:00
2002-01-25 21:33:10 +00:00