On Tue, 2007-10-16 at 14:28 -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote: > From: James Bottomley <James.Bottomley@xxxxxxxxxxxx> > > On Sun, 2007-10-14 at 12:21 -0700, Andrew Morton wrote: > > On Sun, 14 Oct 2007 22:45:47 +0400 "Dave Milter" <davemilter@xxxxxxxxx> wrote: > > > > > I build linux-2.6.23-mm1 and try to boot it using qemu, > > > and it crashed with trace like this: > > > do_page_fault > > > error_code > > > lock_acquire > > > _spin_lock_irqsave > > > gdth_timeout > > > run_timer_softirq > > > __do_softirq > > > do_softirq > > > > > > I have screenshot, but have no idea, is it legal to include it, if I > > > sent copy to lkml. > > > config of kernel in attachment, > > > I apply all three patches from hot-fixes. > > > > > > > The screenshot is here: http://userweb.kernel.org/~akpm/crash.png > > > > It would appear that gdth_timeout() is passing a bad pointer into > > spin_lock_irqsave(). > > There's a bug in the gdth rework in that the instance can be deleted > from the list before the actual timer is stopped. This can be worked > around I think by the following patch; although we really should be > stopping the timer from firing when the list goes empty. > > > > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > drivers/scsi/gdth.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff -puN drivers/scsi/gdth.c~git-scsi-misc-gdth-fix drivers/scsi/gdth.c > --- a/drivers/scsi/gdth.c~git-scsi-misc-gdth-fix > +++ a/drivers/scsi/gdth.c > @@ -3793,6 +3793,9 @@ static void gdth_timeout(ulong data) > gdth_ha_str *ha; > ulong flags; > > + if (list_empty(&gdth_instances)) > + return; > + > ha = list_first_entry(&gdth_instances, gdth_ha_str, list); > spin_lock_irqsave(&ha->smp_lock, flags); > This is almost certainly the wrong fix for real hardware. Although it kills the timer when the list goes empty, nothing will ever restart it when the list fills again. Boaz, since you touched all of this, you get to fix it. The correct fix will be to control the timer along with the actual list instead of at entry/exit time. If you're not going to add this empty check to the timer routine, make sure you use del_timer_sync() before removing the last element from the list. James - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
