mutex lock assertion panic in vm_page_free() on sparc64

[Alan Cox]

On Tue, Feb 22, 2005 at 04:27:11PM +0200, Ruslan Ermilov wrote:
> On Tue, Feb 22, 2005 at 01:03:18PM +0200, Ruslan Ermilov wrote:
> > Hi,
> > 
> > I'm repeatedly getting the following panic (three-four times a day)
> > on sparc64 running a fresh -CURRENT, building world:
> > 
> > db> show msgbuf
> > panic: mutex vm object not owned at /usr/src/sys/vm/vm_page.c:608
> > cpuid = 0
> > KDB: enter: panic
> > exclusive sleep mutex vm page queue mutex r = 0 (0xc04be700) locked @ /usr/src/sys/sparc64/sparc64/vm_machdep.c:483
> > exclusive sleep mutex UMA lock r = 0 (0xc04bdcc0) locked @ /usr/src/sys/vm/uma_core.c:1485
> > exclusive sleep mutex Giant r = 0 (0xc0422728) locked @ /usr/src/sys/vm/vm_pageout.c:666
> > db> where
> > Tracing pid 7 tid 100016 td 0xfffff80067c0c720
> > panic() at panic+0x16c
> > _mtx_assert() at _mtx_assert+0x6c
> > vm_page_remove() at vm_page_remove+0x34
> > vm_page_free_toq() at vm_page_free_toq+0xb8
> > vm_page_free() at vm_page_free+0x10
> > uma_small_free() at uma_small_free+0x54
> > zone_drain() at zone_drain+0x2e8
> > zone_foreach() at zone_foreach+0x3c
> > uma_reclaim() at uma_reclaim+0x10
> > vm_pageout_scan() at vm_pageout_scan+0x13c
> > vm_pageout() at vm_pageout+0x3e8
> > fork_exit() at fork_exit+0x9c
> > fork_trampoline() at fork_trampoline+0x8
> > 
> I have no idea if this is the correct fix or not, but the necessary
> vm_object_t locking is certainly missing in uma_small_free() on all
> architectures implementing it (alpha, amd64, ia64, powerpc, and
> sparc64).

It is not.  Take a look at uma_small_alloc().  You'll see that pages
are allocated with the option VM_ALLOC_NOOBJ, meaning that they are
not members of any vm object.  Consequently, the page's object field
should remain NULL and vm_page_remove() should never be executed.  I'm
afraid that something is trashing your vm_page_array.  Could you print
the contents of the offending page structure?

Alan