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Commit 43e01fef authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Greg Kroah-Hartman
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ARM: 8840/1: use a raw_spinlock_t in unwind 



[ Upstream commit 74ffe79ae538283bbf7c155e62339f1e5c87b55a ]

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);

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent db3ef3e5

arch/arm/kernel/unwind.c

+7 −7
Original line number Diff line number Diff line
@@ -93,7 +93,7 @@ extern const struct unwind_idx __start_unwind_idx[]; 
static const struct unwind_idx *__origin_unwind_idx;

extern const struct unwind_idx __stop_unwind_idx[];



static DEFINE_SPINLOCK(unwind_lock);

static DEFINE_RAW_SPINLOCK(unwind_lock);

static LIST_HEAD(unwind_tables);



/* Convert a prel31 symbol to an absolute address */
@@ -201,7 +201,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr) 
		/* module unwind tables */

		struct unwind_table *table;



		spin_lock_irqsave(&unwind_lock, flags);

		raw_spin_lock_irqsave(&unwind_lock, flags);

		list_for_each_entry(table, &unwind_tables, list) {

			if (addr >= table->begin_addr &&

			    addr < table->end_addr) {
@@ -213,7 +213,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr) 
				break;

			}

		}

		spin_unlock_irqrestore(&unwind_lock, flags);

		raw_spin_unlock_irqrestore(&unwind_lock, flags);

	}



	pr_debug("%s: idx = %p\n", __func__, idx);
@@ -529,9 +529,9 @@ struct unwind_table *unwind_table_add(unsigned long start, unsigned long size, 
	tab->begin_addr = text_addr;

	tab->end_addr = text_addr + text_size;



	spin_lock_irqsave(&unwind_lock, flags);

	raw_spin_lock_irqsave(&unwind_lock, flags);

	list_add_tail(&tab->list, &unwind_tables);

	spin_unlock_irqrestore(&unwind_lock, flags);

	raw_spin_unlock_irqrestore(&unwind_lock, flags);



	return tab;

}
@@ -543,9 +543,9 @@ void unwind_table_del(struct unwind_table *tab) 
	if (!tab)

		return;



	spin_lock_irqsave(&unwind_lock, flags);

	raw_spin_lock_irqsave(&unwind_lock, flags);

	list_del(&tab->list);

	spin_unlock_irqrestore(&unwind_lock, flags);

	raw_spin_unlock_irqrestore(&unwind_lock, flags);



	kfree(tab);

}