Mostly unwind is done with irqs enabled however SLUB may call it with
irqs disabled while creating a new SLUB cache.
I had system freeze while loading a module which called
kmem_cache_create() on init. That means SLUB's __slab_alloc() disabled
interrupts and then
->new_slab_objects()
->new_slab()
->setup_object()
->setup_object_debug()
->init_tracking()
->set_track()
->save_stack_trace()
->save_stack_trace_tsk()
->walk_stackframe()
->unwind_frame()
->unwind_find_idx()
=>spin_lock_irqsave(&unwind_lock);
I would prefer not to turn this into a raw lock so for now it will just
fail if it is called with irqs disabled which might return a few "empty"
traces…
Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
---
arch/arm/kernel/unwind.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 00df012..2af232d 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -195,6 +195,11 @@ static const struct unwind_idx *unwind_find_idx(unsigned
long addr)
/* module unwind tables */
struct unwind_table *table;
+#ifdef CONFIG_PREEMPT_RT_FULL
+ if (irqs_disabled())
+ goto out;
+#endif
+
spin_lock_irqsave(&unwind_lock, flags);
list_for_each_entry(table, &unwind_tables, list) {
if (addr >= table->begin_addr &&
@@ -211,6 +216,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned
long addr)
}
pr_debug("%s: idx = %p\n", __func__, idx);
+out:
return idx;
}
@@ -345,7 +351,9 @@ int unwind_frame(struct stackframe *frame)
idx = unwind_find_idx(frame->pc);
if (!idx) {
+#ifndef CONFIG_PREEMPT_RT_FULL
pr_warning("unwind: Index not found %08lx\n", frame->pc);
+#endif
return -URC_FAILURE;
}
--
1.8.5.3
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