The problem was due to an interaction between the doomed unmounts done by
amd and getnewvnode.
I convinced myself that it's ok for getnewvnode() to do a sleeping vfs_busy().
Tested with multiple builds running while another process attempted to unmount
/usr once a second.
too. Remove some needless code duplication by adding a "drain" argument
to the ACQUIRE() macro (compiler can [and does] optimize the constant
conditional).
free a PV page if the PV entry was associated with the kernel pmap,
since the kernel pmap is locked, and freeing the page will execute
a code path which will attempt to lock it again, resulting in deadlock.
No real loss, since the next time a PV entry is freed, the page will
be freed, too.
locking primitive directly to lock it, since those will never attempt
to call printf() to display debugging information (and thus deadlock
on recursion into the kprintf_slock).
- Now compatible with MULTIPROCESSOR (requires other changes not yet
committed, but which will be later today).
- In addition to tracking simple locks, track exclusive spin locks.
- Count spin locks like we do sleep locks (in the cpu_info for this
CPU).
- Lock debug lists are now TAILQs, so as to make the locking order
more obvious when dumping the list.
Also, some suggestions from Bill Sommerfeld:
- SIMPLELOCK_LOCKED and SIMPLELOCK_UNLOCKED constants, which may be
defined in <machine/lock.h> (default to 1 and 0, respectively). This
makes it easier to support architectures which use test-and-clear
rather than test-and-set.
- Add __attribute__((__aligned__)) to the `lock_data' member of the
simplelock structure. This makes it easier to support architectures
which can only perform atomic operations on very-well-aligned memory
locations. NOTE: This changes the size of struct simplelock, and
will cause a version bump.
once for ipv6. This patch makes the ipv6 case pass NULLs in for fast
and slow timeouts iff defined(INET) and passes in the right function
if !defined(INET).
Reveiwed by itojun@iijlab.net.
