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List:       freebsd-bugs
Subject:    kern/68076: Page fault when the sequence "kldunload ucom",
From:       Juan.Fco.Rodriguez.Hervella () cimborrio ! ipv6 ! it ! uc3m ! es, jrh () it ! uc3m ! es
Date:       2004-06-18 11:22:04
Message-ID: 200406181122.i5IBM4gE000874 () cimborrio ! ipv6 ! it ! uc3m ! es
[Download RAW message or body]


> Number:         68076
> Category:       kern
> Synopsis:       Page fault when the sequence "kldunload ucom", "kldunload uplcom" is executed
> Confidential:   no
> Severity:       non-critical
> Priority:       low
> Responsible:    freebsd-bugs
> State:          open
> Quarter:        
> Keywords:       
> Date-Required:
> Class:          sw-bug
> Submitter-Id:   current-users
> Arrival-Date:   Fri Jun 18 11:30:27 GMT 2004
> Closed-Date:
> Last-Modified:
> Originator:     Juan Fco Rodriguez Hervella
> Release:        FreeBSD 4.10-STABLE i386
> Organization:
University Carlos III of Madrid (Spain)
> Environment:
System: FreeBSD cimborrio.ipv6.it.uc3m.es 4.10-STABLE FreeBSD 4.10-STABLE #7: Fri May 28 \
17:23:51 CEST 2004 root@cimborrio.ipv6.it.uc3m.es:/usr/src/sys/compile/JUANILLO i386


	hp/compaq nx9010
> Description:
	I've got a USB to serial cable. It works quite well. When I unload "uplcom",
	there is no problem, and automatically the "ucom" module dissapears. When
	I do it the other way, firstly "kldunload ucom" and afterwards "kldunload uplcom",
	a page faul appears and the laptop reboots. I've made a small debugging and
	the problem seems to be that it tries to unload the "ucom" driver, because it's
	a dependency, but it doesn't find it and something goes wrong... This is
	an excerpt of the debugging, in case it helps:

(kgdb) bt
#0  dumpsys () at ../../kern/kern_shutdown.c:487
#1  0xc026b17f in boot (howto=256) at ../../kern/kern_shutdown.c:316
#2  0xc026b5a4 in poweroff_wait (junk=0xc047e26c, howto=-1069032081) at \
../../kern/kern_shutdown.c:595 #3  0xc03e2d5a in trap_fatal (frame=0xcc76beac, eva=334) at \
../../i386/i386/trap.c:974 #4  0xc03e2a2d in trap_pfault (frame=0xcc76beac, usermode=0, \
eva=334) at ../../i386/i386/trap.c:867 #5  0xc03e25eb in trap (frame={tf_fs = 16, tf_es = \
                -864681968, tf_ds = -1071251440, tf_edi = 0, tf_esi = -1061824384,
      tf_ebp = -864633092, tf_isp = -864633128, tf_ebx = 1, tf_edx = 318, tf_ecx = -868313824, \
                tf_eax = 0, tf_trapno = 12,
      tf_err = 2, tf_eip = -1071271779, tf_cs = 8, tf_eflags = 66050, tf_esp = 1, tf_ss = \
-1061824128})  at ../../i386/i386/trap.c:466
#6  0xc025b09d in linker_file_unload (file=0xc0b5d880) at ../../kern/kern_linker.c:438
#7  0xc025b0df in linker_file_unload (file=0xc0b5d980) at ../../kern/kern_linker.c:442
#8  0xc025b4d5 in kldunload (p=0xcc3e9520, uap=0xcc76bf80) at ../../kern/kern_linker.c:713
#9  0xc03e3009 in syscall2 (frame={tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = 2, tf_esi = \
                -1077936790,
      tf_ebp = -1077937072, tf_isp = -864632876, tf_ebx = 0, tf_edx = 0, tf_ecx = 0, tf_eax = \
                305, tf_trapno = 12,
      tf_err = 2, tf_eip = 134514400, tf_cs = 31, tf_eflags = 647, tf_esp = -1077938172, tf_ss \
= 47})  at ../../i386/i386/trap.c:1175
#10 0xc03d3b95 in Xint0x80_syscall ()
#11 0x804813e in ?? ()

...
#7  0xc025b0df in linker_file_unload (file=0xc0b5d980) at ../../kern/kern_linker.c:442
442             linker_file_unload(file->deps[i]);
(kgdb) list
437
438         TAILQ_REMOVE(&linker_files, file, link);
439         lockmgr(&lock, LK_RELEASE, 0, curproc);
440
441         for (i = 0; i < file->ndeps; i++)
442             linker_file_unload(file->deps[i]);
443         free(file->deps, M_LINKER);
444
445         for (cp = STAILQ_FIRST(&file->common); cp;
446              cp = STAILQ_FIRST(&file->common)) {


         I think the function call "linker_file_upload(file->deps[1])"
	 is a non-sense. Look:

kgdb) p *(linker_file_t)file->deps[1]
$4 = {refs = -1061824257, userrefs = 0, flags = 0, link = {tqe_next = 0x13e, tqe_prev = 0x0}, \
filename = 0x0, id = 0,  address = 0x0, size = 10, ndeps = 0, deps = 0x0, common = {stqh_first \
= 0x0, stqh_last = 0x0}, modules = {  tqh_first = 0x0, tqh_last = 0x0}, priv = 0x0, ops = 0x0}
(kgdb)

Hope this helps. Thank you.

> How-To-Repeat:
	kldunload ucom
	kldunload uplcom
> Fix:

	


> Release-Note:
> Audit-Trail:
> Unformatted:
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