i know this has been reported before. and i've guessed at exactly this problem, but it's happened again here. and this time i have a bit of evidence.
i haven't quite tracked everything down, or what the original problem is (that is, who owns the lock and more importantly, why) but the hang is because of the qlock of p->debug in procopen. minooka# acid -k 55053 /n/dump/2009/0819/386/9pccpu /n/dump/2009/0819/386/9pccpu:386 plan 9 boot image /sys/lib/acid/port /sys/lib/acid/386 acid: stk() sched()+0x12d /sys/src/9/port/proc.c:155 qlock(q=0xf03d9244)+0x141 /sys/src/9/port/qlock.c:48 procopen(omode=0x0,c=0xf6e52ab8)+0x193 /sys/src/9/port/devproc.c:369 namec(aname=0xf709f318,amode=0x3,omode=0x0,perm=0x0)+0x6d9 /sys/src/9/port/chan.c:1491 sysopen(arg=0xf041c1a0)+0xa9 /sys/src/9/port/sysfile.c:279 syscall(ureg=0xf6810e6c)+0x1b5 /sys/src/9/pc/trap.c:712 _syscallintr()+0x18 /sys/src/9/pc/plan9l.s:45 0xf6810e6c ?file?:0 - erik
