On Tue, 18 Mar 2014, Vince Weaver wrote:
> On Tue, 18 Mar 2014, Thomas Gleixner wrote:
> >
> > > [ 3.678040] BUG: unable to handle kernel NULL pointer dereference at
> > > 0000000000000018
> > >
> > > [ 3.686776] IP: [<ffffffff8106d7a8>]
> > > get_next_timer_interrupt+0x168/0x250
> >
> > The back trace is not really helpful. Is there anything before that
> > BUG in dmesg?
>
> no, just normal boot messages.
>
> I re-compiled with the frame pointer enabled and here's an updated
> version:
>
> [ 3.722836] sd 1:0:0:0: [sda] 4096-byte physical blocks
>
> [ 3.728682] sd 1:0:0:0: [sda] Write Protect is off
>
> [ 3.728826] sr 0:0:0:0: Attached scsi generic sg0 type 5
>
> [ 3.728992] sd 1:0:0:0: Attached scsi generic sg1 type 0
>
> [ 3.745700] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled,
> doesn't support DPO or FUA
>
> [ 3.787096] sda: sda1 sda2 sda3 sda4
>
> [ 3.792169] sd 1:0:0:0: [sda] Attached SCSI disk
>
> [ 4.312111] ------------[ cut here ]------------
>
> [ 4.317176] kernel BUG at kernel/timer.c:1084!
>
Wow. That's in the cascade code. So it looks like the timer got
corrupted without using the timer api wrong. That might be a memset or
a stray pointer. Can you apply the following patch?
That really should give us a hint.
If that fails, enable the tracer in your config and add the following
to your commandline
trace_event=timer_* ftrace_dump_on_oops
That will spill out a lot of crap over serial, but it should tell us
which timer is corrupted.
Thanks,
tglx
Index: linux-2.6/include/linux/debugobjects.h
===================================================================
--- linux-2.6.orig/include/linux/debugobjects.h
+++ linux-2.6/include/linux/debugobjects.h
@@ -68,6 +68,7 @@ extern void debug_object_deactivate(void
extern void debug_object_destroy (void *addr, struct debug_obj_descr *descr);
extern void debug_object_free (void *addr, struct debug_obj_descr *descr);
extern void debug_object_assert_init(void *addr, struct debug_obj_descr
*descr);
+extern void debug_object_info(void *addr, struct debug_obj_descr *descr);
/*
* Active state:
@@ -95,6 +96,8 @@ static inline void
debug_object_free (void *addr, struct debug_obj_descr *descr) { }
static inline void
debug_object_assert_init(void *addr, struct debug_obj_descr *descr) { }
+static inline void
+debug_object_info(void *addr, struct debug_obj_descr *descr) { }
static inline void debug_objects_early_init(void) { }
static inline void debug_objects_mem_init(void) { }
Index: linux-2.6/kernel/timer.c
===================================================================
--- linux-2.6.orig/kernel/timer.c
+++ linux-2.6/kernel/timer.c
@@ -1081,7 +1081,12 @@ static int cascade(struct tvec_base *bas
* don't have to detach them individually.
*/
list_for_each_entry_safe(timer, tmp, &tv_list, entry) {
- BUG_ON(tbase_get_base(timer->base) != base);
+ if (tbase_get_base(timer->base) != base) {
+ pr_err("Invalid timer base: tmr %p tmr->base %p base
%p\n",
+ timer, timer->base, base);
+ debug_object_info(timer, &timer_debug_descr);
+ BUG();
+ }
/* No accounting, while moving them */
__internal_add_timer(base, timer);
}
Index: linux-2.6/lib/debugobjects.c
===================================================================
--- linux-2.6.orig/lib/debugobjects.c
+++ linux-2.6/lib/debugobjects.c
@@ -377,6 +377,28 @@ void debug_object_init_on_stack(void *ad
__debug_object_init(addr, descr, 1);
}
+void debug_object_info(void *addr, struct debug_obj_descr *descr)
+{
+ struct debug_bucket *db;
+ struct debug_obj *obj;
+ unsigned long flags;
+
+ if (!debug_objects_enabled)
+ return;
+
+ db = get_bucket((unsigned long) addr);
+
+ raw_spin_lock_irqsave(&db->lock, flags);
+
+ obj = lookup_object(addr, db);
+ if (!obj)
+ pr_err("Object unknown %p\n", addr);
+ else
+ debug_print_object(obj, "Info");
+
+ raw_spin_unlock_irqrestore(&db->lock, flags);
+}
+
/**
* debug_object_activate - debug checks when an object is activated
* @addr: address of the object
--
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