Re: Tmpfs panic in -current

Kevin Lo wrote:
> Konstantin Belousov wrote:
> > On Tue, Jun 26, 2012 at 12:38:25PM +0800, Kevin Lo wrote:
> > > Konstantin Belousov wrote:
> > > > On Mon, Jun 25, 2012 at 10:03:28AM +0800, Kevin Lo wrote:
> > > > > I've observed a panic in recent -current several times but I only
> > > > > have a picture of the backtrace:
> > > > > http://people.freebsd.org/~kevlo/panic_tmpfs.jpg
> > > > > 
> > > > > Does this look at all familiar to anyone?
> > > > 
> > > > Can you look up the line corresponding to tmpfs_reg_resize + 0x627 address
> > > > in your kernel ?
> > > 
> > > Sure.
> > > 
> > > > The screenshot looks strange. The instruction on which the kernel trapped
> > > > is int 0x28 which should not appear in the compiled code.
> > > 
> > > # gdb tmpfs.ko
> > > (gdb) l *tmpfs_reg_resize+0x627
> > > 0xbf37 is in tmpfs_reg_resize (/usr/src/sys/modules/tmpfs/../../fs/tmpfs/tmpfs_subr.c:1005).
> > > 1000    in /usr/src/sys/modules/tmpfs/../../fs/tmpfs/tmpfs_subr.c
> > > 
> > > In tmpfs_subr.c:
> > >  999                         if (m != NULL) {
> > > 1000                                 if ((m->oflags & VPO_BUSY) != 0 ||
> > > 1001                                     m->busy != 0) {
> > > 1002                                         vm_page_sleep(m, "tmfssz");
> > > 1003                                         goto retry;
> > > 1004                                 }
> > > 1005                                 MPASS(m->valid == VM_PAGE_BITS_ALL);
> > > 1006                         } else if (vm_pager_has_page(uobj, idx, NULL, NU
> > > LL)) {
> > > 
> > Hm, can you get a core and
> > - obtain backtrace in kgdb;
> > - print the *m content for the page that triggered the assertion ?
> > 
> > The only possible 'new size' value for the truncation from open(2) is zero,
> > so I do not understand why the asserted block was executed at all.
> 
> Thanks for looking into it. Unfortunately I can't get a crash dump 
> due to lack of disk space and memory.

I triggered the KASSERT on a different machine in the last hour.

panic: Assertion (vp) !=NULL && (vp)->v_data != NULL failed at 
_at_/fs/tmpfs/tmpfs.h:527

The bad news is my coworker rebooted that machine after panic :-(

	Kevin