Doug Rabson wrote:
> On Sat, 23 Jan 1999, Matthew Dillon wrote:
>
> >
> > :I made it happen again by doing the same installworld but this time I
> > :caught it in the debugger. I'll leave the machine up for a while in case
> > :someone has some idea of how to debug it. The stacktrace looks like this:
> > :
> > :#0 Debugger () at ../../alpha/alpha/db_interface.c:260
> > :#1 0xfffffc000036c2c0 in panic () at ../../kern/kern_shutdown.c:444
> > :#2 0xfffffc00004942fc in vm_page_alloc () at ../../vm/vm_page.c:1041
> > :#3 0xfffffc00003a1b54 in allocbuf () at ../../kern/vfs_bio.c:1791
> >
> > The panic message should be printing the address of the vm_page_t that
> > it caught.
> >
> > From the debugger, dump that vm_page_t with 'print'.
> >
> > print *0xADDRESS
> >
> > Do about 8 print's bumping the address by 4 ( in hex ) for each.
> >
> > It would be even better if we could figure out the contents and type
> > of the underlying object.
>
> I have full symbols:
>
> (gdb) fr 2
> #2 0xfffffc00004942fc in vm_page_alloc () at ../../vm/vm_page.c:1041
> 1041 panic("found dirty cache page %p", m);
> (gdb) l
> 1036 */
> 1037
> 1038 if (qtype == PQ_CACHE) {
> 1039 #if !defined(MAX_PERF)
> 1040 if (m->dirty)
> 1041 panic("found dirty cache page %p", m);
> 1042
> 1043 #endif
> 1044 vm_page_busy(m);
> 1045 vm_page_protect(m, VM_PROT_NONE);
> (gdb) p m
> $4 = (struct vm_page *) 0xfffffe0000108f40
> (gdb) p *m
> $5 = {pageq = {tqe_next = 0x0, tqe_prev = 0xfffffc000052ecc8}, hnext = 0x0,
> listq = {tqe_next = 0xfffffe0000090fe0, tqe_prev = 0xfffffe00000bb6b8},
> object = 0xfffffe00050e2a10, pindex = 12, phys_addr = 88940544, queue = 172
,
> flags = 128, pc = 41, wire_count = 0, hold_count = 0, act_count = 5 '\005',
> busy = 0 '\000', valid = 65535, dirty = 65535}
> --
Doug, Matt wanted some things from m->object too.. If it's still there
can you grab it?
printf(
"found dirty cache page %p (%p,%d,%x) obtype %d obflags %x",
m,
m->object,
(int)m->pindex,
(int)m->flags,
(int)m->object->type,
(int)m->object->flags
);
BTW; in vm_map.c:
/*
* vm_map_clean
*
* Push any dirty cached pages in the address range to their pager.
* If syncio is TRUE, dirty pages are written synchronously.
* If invalidate is TRUE, any cached pages are freed as well.
*
* Returns an error if any part of the specified range is not mapped.
*/
This kinda suggests that dirty cached pages might not be all that
unusual.. but the code in question seems to be working at a different
level.
Cheers,
-Peter
--
Peter Wemm <pe...@netplex.com.au> Netplex Consulting
"No coffee, No workee!" :-)
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