[Bug 207085] pmc assertion failure: pmc %p non-NULL

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=207085

--- Comment #3 from joss.upton at yahoo.com ---
(In reply to Konstantin Belousov from comment #1)
Here's the state of the machine during one of these panics (back trace at the
bottom).

There are four instances of "monitor" and four instances of "target" in the
system.  Monitor aloocates/attaches pmc's to target and then waits for target
to exit. It then reads the pmcs, releases them, and exits.

panicstr: [soft,327] PHW pmc 0xfffff800b411ec80 non-NULL
cpuid = 0

which corresponds to:

static int soft_release_pmc(int cpu, int ri, struct pmc *pmc) {
 ...
 KASSERT(phw->phw_pmc == NULL,
            ("[soft,%d] PHW pmc %p non-NULL", __LINE__, phw->phw_pmc));
 ...
}


pmc->owner is "monitor" (pid=19085, td_oncpu=0)

pmc->pm_targets list is empty.

pmc->owner->children has one entry "target" (pid=19086, td_oncpu=0xff,
td_lastcpu=0).  This child is a zombie.

Looking at phw->phw_pmc:
phw->phw_pmc->pm_phw: owner is "monitor" (pid=19087, td_oncpu=0xff,
td_lastcpu=0)

phw->phw_pmc->pm_targets = "target" (pid=19088, td_oncpu=0xff, td_lastcpu=1).

phw->phw_pmc->pm_owner->children: "target" (pid=19088, td_oncpu=0xff,
td_lastcpu=1).

panic: [soft,327] PHW pmc 0xfffff800b411ec80 non-NULL
cpuid = 0
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0239efe650
kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe0239efe700
vpanic() at vpanic+0x126/frame 0xfffffe0239efe740
kassert_panic() at kassert_panic+0x195/frame 0xfffffe0239efe7d0
soft_release_pmc() at soft_release_pmc+0xb9/frame 0xfffffe0239efe800
pmc_release_pmc_descriptor() at pmc_release_pmc_descriptor+0x33b/frame
0xfffffe0239efe850
pmc_syscall_handler() at pmc_syscall_handler+0x158b/frame 0xfffffe0239efeac0
amd64_syscall() at amd64_syscall+0x2b3/frame 0xfffffe0239efebf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0239efebf0
--- syscall (0, FreeBSD ELF64, nosys), rip = 0x802699a2a, rsp = 0x7fffffffe468,
rbp = 0x7fffffffe480 ---
KDB: enter: panic

#0  doadump (textdump=0) at pcpu.h:220
220     pcpu.h: No such file or directory.
        in pcpu.h
(kgdb) #0  doadump (textdump=0) at pcpu.h:220
#1  0xffffffff802f3a0e in db_dump (dummy=<value optimized out>, dummy2=0,
    dummy3=0, dummy4=0x0) at /vagrant/usr/src/sys/ddb/db_command.c:533
#2  0xffffffff802f34ad in db_command (cmd_table=0x0)
    at /vagrant/usr/src/sys/ddb/db_command.c:440
#3  0xffffffff802f778f in db_script_exec (
    scriptname=0xfffffe0239efe300 "kdb.enter.panic",
    warnifnotfound=<value optimized out>)
    at /vagrant/usr/src/sys/ddb/db_script.c:302
#4  0xffffffff802f75d3 in db_script_kdbenter (eventname=0x0)
    at /vagrant/usr/src/sys/ddb/db_script.c:324
#5  0xffffffff802f5c9b in db_trap (type=<value optimized out>, code=0)
    at /vagrant/usr/src/sys/ddb/db_main.c:230
#6  0xffffffff805a0529 in kdb_trap (type=3, code=0, tf=<value optimized out>)
    at /vagrant/usr/src/sys/kern/subr_kdb.c:656
#7  0xffffffff8079709e in trap (frame=0xfffffe0239efe630)
    at /vagrant/usr/src/sys/amd64/amd64/trap.c:564
#8  0xffffffff8077ac72 in calltrap ()
    at /vagrant/usr/src/sys/amd64/amd64/exception.S:236
#9  0xffffffff8059fc8e in kdb_enter (why=0xffffffff808949a1 "panic",
    msg=<value optimized out>) at cpufunc.h:63
#10 0xffffffff80563326 in vpanic (fmt=<value optimized out>,
    ap=<value optimized out>) at /vagrant/usr/src/sys/kern/kern_shutdown.c:751
#11 0xffffffff805631d5 in kassert_panic (fmt=<value optimized out>)
    at /vagrant/usr/src/sys/kern/kern_shutdown.c:646
#12 0xffffffff8038d9d9 in soft_release_pmc (cpu=<value optimized out>,
    ri=<value optimized out>, pmc=0xfffff800b411c180)
    at /vagrant/usr/src/sys/dev/hwpmc/hwpmc_soft.c:326
#13 0xffffffff8038a4bb in pmc_release_pmc_descriptor (pm=0xfffff800b411c180)
    at /vagrant/usr/src/sys/dev/hwpmc/hwpmc_mod.c:2360
#14 0xffffffff8038853b in pmc_syscall_handler (td=<value optimized out>,
    syscall_args=<value optimized out>)
    at /vagrant/usr/src/sys/dev/hwpmc/hwpmc_mod.c:3685
#15 0xffffffff80797f83 in amd64_syscall (td=0xfffff800b4d3c000, traced=0)
    at subr_syscall.c:134
#16 0xffffffff8077af5b in Xfast_syscall ()
    at /vagrant/usr/src/sys/amd64/amd64/exception.S:396
#17 0x0000000802699a2a in ?? ()

-- 
You are receiving this mail because:
You are on the CC list for the bug.