Date: Fri, 16 Mar 2001 17:21:54 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: freebsd-alpha@freebsd.org Cc: jhb@freebsd.org Subject: user process faulting on kernel address Message-ID: <15026.37378.477855.889651@grasshopper.cs.duke.edu>
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When running a linuxthreads app which basically sits in a loop
doing a pthread_create()/pthread_join() of a thread which just
exits, I'll occasionally see a very interesting thing --
the app dies on an instruction fault on a kernel address.
Enabling the DEBUG printtrap() calls in trap yeilds this information:
login:
fatal user trap:
trap entry = 0x2 (memory management fault)
a0 = 0xfffffc0000418be0
a1 = 0x1
a2 = 0xffffffffffffffff
pc = 0xfffffc0000418be0
ra = 0x11ffbfc4
curproc = 0xfffffe0006824cc0
pid = 18788, comm = ex6
Note that it is an instruction fault (a2 == -1) and the faulting
address maps to the bottom of witness_exit:
(kgdb) l *0xfffffc0000418be0
0xfffffc0000418be0 is in witness_exit (../../kern/kern_mutex.c:1262).
1257 m->mtx_line = line;
1258 m->mtx_file = file;
1259 p = curproc;
1260 MPASS(m->mtx_held.le_prev == NULL);
1261 LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held);
1262 }
1263
1264 void
1265 witness_exit(struct mtx *m, int flags, const char *file, int line)
1266 {
The $ra looks reasonable, it is at least a userspace stack address.
I think somebody saw this a while ago, but I cannot find their
message..
Any ideas?
Drew
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