On Wed, Mar 23, 2011 at 09:45:37AM -0400, John Baldwin wrote: > On Friday, March 18, 2011 4:40:34 am Julian Elischer wrote: > > On 3/17/11 11:47 PM, Edward Tomasz Napierala wrote: > > > Author: trasz > > > Date: Fri Mar 18 06:47:23 2011 > > > New Revision: 219727 > > > URL: http://svn.freebsd.org/changeset/base/219727 > > > > > > Log: > > > In vm_daemon(), when iterating over all processes in the system, skip > > > those > > > which are not yet fully initialized (i.e. ones with p_state == > > > PRS_NEW). > > > Without it, we could panic in _thread_lock_flags(). > > > > > > Note that there may be other instances of FOREACH_PROC_IN_SYSTEM() that > > > require similar fix. > > > > In the past each process was only put on the process list after it was > > fully set up. > > Did someone change that recently? that would be "A Bad Thing" (TM). > > Err, no, that has never been true. The reason it has to go on the list > immediately is to reserve the PID against concurrent fork()s. > > Hmm, the locking of prs_state is a bit busted it seems. Both the PROC_LOCK() > and PROC_SLOCK() are supposed to be held when it is written to, but > PROC_LOCK() is missing in fork1() when moving the state to PRS_NORMAL. > > Also, this commit should check against PRS_NORMAL after acquiring the proc > lock, not before. In the case of this commit, it does not matter much, I think. The reason is that all the check want is to make sure that there is at least one fully initialized thread linked into the process.
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