Date: Tue, 19 Mar 1996 02:09:09 +0900 From: KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp> To: p.richards@elsevier.co.uk Cc: freebsd-current@freebsd.org Subject: Re: Whee! Page Fault! Message-ID: <199603181709.CAA00868@marble.eps.nagoya-u.ac.jp> In-Reply-To: Your message of "Mon, 18 Mar 1996 15:45:38 GMT" References: <199603181545.PAA04484@tees>
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> but I'm not sure it's the only cause since I wasn't using the cdrom the
> first time it happened.
I don't access CDROM, but I also have numerous panics, and couldn't
boot FreeBSD-current box. For example, After fsck in rc, my 5x86 box
shows following messages:
panic: freeing held page, count=1
Debugger("panic")
Stopped at _Debugger+0x2a: movb $0,_in_Debugger.110
_Debugger(f0b48800,5800,1,0,f0b48864) at _Debugger+0x2a
_trap_pfault(0,0,1,1,0) at _trap_pfault+0x10a
(null)(10000,10,2,0,1) at 0
(null)(0,0,0,0,0) at 0
and
v_page_free: pindex(14), busy(0), PG_BUSY(0)
panic: vm_page_free: freeing free page
I changed the code in vm_map_simplify_entry into revision 1.37 of
vm_map.c by following patch:
--------------------
*** vm_map.c.orig Tue Mar 19 01:15:37 1996
--- vm_map.c Tue Mar 19 01:15:20 1996
***************
*** 844,898 ****
* neighbors.
*/
! if (entry->is_sub_map || entry->is_a_map || entry->wired_count)
return;
! prev = entry->prev;
! if (prev != &map->header) {
prevsize = prev->end - prev->start;
! if ( prev->end == entry->start &&
! prev->object.vm_object == entry->object.vm_object &&
! prev->offset + prevsize == entry->offset &&
! prev->protection == entry->protection &&
! prev->max_protection == entry->max_protection &&
! prev->inheritance == entry->inheritance &&
! prev->needs_copy == entry->needs_copy &&
! prev->copy_on_write == entry->copy_on_write &&
! prev->is_a_map == FALSE &&
! prev->is_sub_map == FALSE &&
! prev->wired_count == 0) {
! if (map->first_free == prev)
! map->first_free = entry;
! vm_map_entry_unlink(map, prev);
! entry->start = prev->start;
! entry->offset = prev->offset;
! vm_object_deallocate(prev->object.vm_object);
! vm_map_entry_dispose(map, prev);
! }
! }
!
! next = entry->next;
! if (next != &map->header) {
nextsize = next->end - next->start;
esize = entry->end - entry->start;
! if (entry->end == next->start &&
! next->object.vm_object == entry->object.vm_object &&
! entry->offset + esize == next->offset &&
! next->protection == entry->protection &&
! next->max_protection == entry->max_protection &&
! next->inheritance == entry->inheritance &&
! next->needs_copy == entry->needs_copy &&
! next->copy_on_write == entry->copy_on_write &&
! next->is_a_map == FALSE &&
! next->is_sub_map == FALSE &&
! next->wired_count == 0) {
! if (map->first_free == next)
! map->first_free = entry;
! vm_map_entry_unlink(map, next);
! entry->end = next->end;
! vm_object_deallocate(next->object.vm_object);
! vm_map_entry_dispose(map, next);
! }
}
}
--- 848,904 ----
* neighbors.
*/
! if (entry->is_sub_map)
return;
+ if (entry->is_a_map) {
+ return;
+ } else {
+ if (entry->wired_count)
+ return;
! prev = entry->prev;
prevsize = prev->end - prev->start;
! next = entry->next;
nextsize = next->end - next->start;
esize = entry->end - entry->start;
!
! if (prev != &map->header &&
! prev->end == entry->start &&
! prev->is_a_map == FALSE &&
! prev->is_sub_map == FALSE &&
! prev->object.vm_object == entry->object.vm_object &&
! prev->protection == entry->protection &&
! prev->max_protection == entry->max_protection &&
! prev->inheritance == entry->inheritance &&
! prev->needs_copy == entry->needs_copy &&
! prev->copy_on_write == entry->copy_on_write &&
! prev->offset + prevsize == entry->offset &&
! prev->wired_count == 0) {
! vm_map_entry_unlink(map, prev);
! entry->start = prev->start;
! entry->offset = prev->offset;
! vm_object_deallocate(prev->object.vm_object);
! vm_map_entry_dispose(map, prev);
! esize = entry->end - entry->start;
! }
!
! if (next != &map->header &&
! entry->end == next->start &&
! next->is_a_map == FALSE &&
! next->is_sub_map == FALSE &&
! next->object.vm_object == entry->object.vm_object &&
! next->protection == entry->protection &&
! next->max_protection == entry->max_protection &&
! next->inheritance == entry->inheritance &&
! next->needs_copy == entry->needs_copy &&
! next->copy_on_write == entry->copy_on_write &&
! entry->offset + esize == next->offset &&
! next->wired_count == 0) {
! vm_map_entry_unlink(map, next);
! entry->end = next->end;
! vm_object_deallocate(next->object.vm_object);
! vm_map_entry_dispose(map, next);
! }
}
}
--------------------
After applying this patch, my FreeBSD box works without panic for 12
hours until now.
----
KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp>
Dept. Earth Planet. Sci., Nagoya Univ., Nagoya, 464-01, Japan
Voice: +81-52-789-2529 Fax: +81-52-789-3033
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