Date: Thu, 20 Nov 1997 11:53:34 -0800 (PST) From: Matt Dillon <dillon@best.net> To: FreeBSD-gnats-submit@FreeBSD.ORG Subject: kern/5108: Kernel panic in pmap_release during wait4 Message-ID: <199711201953.LAA04207@flea.best.net> Resent-Message-ID: <199711202000.MAA01979@hub.freebsd.org>
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>Number: 5108
>Category: kern
>Synopsis: pmap_release panics with 'freeing held page table page'
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Nov 20 12:00:01 PST 1997
>Last-Modified:
>Originator: Matt Dillon
>Organization:
Best Internet Communications
>Release: FreeBSD 2.2.5-STABLE i386
>Environment:
FreeBSD 2.2.5 on PPro 200, medium to heavily loaded systems
>Description:
We got a kernel panic 'pmap_release: freeing held page table page'.
We got a core. The backtrace showed:
...
#7 0xf01be634 in trap (frame={tf_es = 0x10, tf_ds = 0x10,
tf_edi = 0xf97cc000, tf_esi = 0xf01bb38a, tf_ebp = 0xefbffe94,
tf_isp = 0xefbffe78, tf_ebx = 0x100, tf_edx = 0xf01b5051,
tf_ecx = 0x3f9, tf_eax = 0x12, tf_trapno = 0x3, tf_err = 0x0,
tf_eip = 0xf01b5089, tf_cs = 0x8, tf_eflags = 0x256,
tf_esp = 0xf01b5041, tf_ss = 0xf01131f8}) at ../../i386/i386/trap.c:403
#8 0xf01b5089 in Debugger (msg=0xf01131f8 "panic")
at ../../i386/i386/db_interface.c:254
#9 0xf011325a in panic (
fmt=0xf01bb38a "pmap_release: freeing held page table page")
at ../../kern/kern_shutdown.c:388
#10 0xf01bb455 in pmap_release_free_page (pmap=0xf2d3d864, p=0xf0aead08)
at ../../i386/i386/pmap.c:1072
#11 0xf01bb69f in pmap_release (pmap=0xf2d3d864) at ../../i386/i386/pmap.c:1260
#12 0xf01a6708 in vmspace_free (vm=0xf2d3d800) at ../../vm/vm_map.c:262
#13 0xf01bf33d in cpu_wait (p=0xf288b800) at ../../i386/i386/vm_machdep.c:650
#14 0xf010cef5 in wait1 (q=0xf2392000, uap=0xefbfff94, retval=0xefbfff84,
compat=0x0) at ../../kern/kern_exit.c:460
#15 0xf010cd23 in wait4 (p=0xf2392000, uap=0xefbfff94, retval=0xefbfff84)
at ../../kern/kern_exit.c:357
#16 0xf01bf077 in syscall (frame={tf_es = 0x27, tf_ds = 0x27,
tf_edi = 0xefbfdd8c, tf_esi = 0xa168, tf_ebp = 0xefbfdca8,
tf_isp = 0xefbfffe4, tf_ebx = 0x20084060, tf_edx = 0x13, tf_ecx = 0x0,
tf_eax = 0x7, tf_trapno = 0x7, tf_err = 0x7, tf_eip = 0x2004e0a1,
tf_cs = 0x1f, tf_eflags = 0x216, tf_esp = 0xefbfdc90, tf_ss = 0x27})
at ../../i386/i386/trap.c:890
It appears that inetd was trying to do a wait4 on a telnetd sub process
when the crash occured. There were around 40 telnetd processes running
at the time.
At a guess I would say vmspace_free has a race with other telnetd's
that might be exiting orforking at the same time. I dunno.
>How-To-Repeat:
no idea.
>Fix:
no idea.
>Audit-Trail:
>Unformatted:
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