From: Sebastian Andrzej Siewior Date: Fri, 20 Sep 2013 14:31:54 +0200 Subject: arm/unwind: use a raw_spin_lock Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.1-rt3.tar.xz 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: Sebastian Andrzej Siewior --- arch/arm/kernel/unwind.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- a/arch/arm/kernel/unwind.c +++ b/arch/arm/kernel/unwind.c @@ -93,7 +93,7 @@ extern const struct unwind_idx __start_u 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_f /* 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_f 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(un 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_tabl 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); }