Date: Tue, 28 Feb 1995 05:56:28 +1100 From: Bruce Evans <bde@zeta.org.au> To: ROBIN@ptnsct.nis.za, davidg@Root.COM Cc: bugs@FreeBSD.org Subject: Re: MB_MAP FULL SYSTEM CRASH Message-ID: <199502271856.FAA16373@godzilla.zeta.org.au>
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>>Now the old girl occasionaly (on a whim) says: "MB_MAP FULL" and crashes
>>completely so it has to be reset.
> The mb_map full message is only generated once and is just informational.
>Are you sure that the panic occurs just after this appears, or is it possible
>that it occurred sometime earlier?
>>Any ideas to help?
> I need more information before I can help. I need the panic message and any
>additional information that may be printed before it.
I thought this was well known. kmem_malloc() panics if mb_map is full
and (waitflag == M_WAITOK). If (waitflag != M_WAITOK) when the map is
first found to be full, then m_clalloc() prints "mb map full". If the
full condition persists, then kmem_malloc() eventually gets called with
(waitflag == M_WAITOK) and panics with the message "kmem_malloc: map too
small" (it stupidly doesn't tell you which map).
I use the following kludgy fix. It works because all allocations of
mb_map go through ml_clalloc(), and ml_clalloc() handles the NULL return
value even in the M_WAITOK case.
Another problem is that if mb_map fills up due to transient loads, the
1 or 2MB of memory in it is never released. This would not work well
on systems with 2 or 4MB of memory.
Bruce
*** vm_kern.c~ Wed Feb 22 08:49:18 1995
--- vm_kern.c Wed Feb 22 08:49:47 1995
***************
*** 303,313 ****
if (vm_map_findspace(map, 0, size, &addr)) {
vm_map_unlock(map);
! #if 0
! if (canwait) /* XXX should wait */
! panic("kmem_malloc: %s too small",
! map == kmem_map ? "kmem_map" : "mb_map");
! #endif
! if (waitflag == M_WAITOK)
! panic("kmem_malloc: map too small");
return (0);
}
--- 303,308 ----
if (vm_map_findspace(map, 0, size, &addr)) {
vm_map_unlock(map);
! if (waitflag == M_WAITOK && map != mb_map)
! panic("kmem_malloc: kmem_map too small");
return (0);
}
help
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