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    Subject[PATCH AUTOSEL 4.14 041/123] ARM: 8840/1: use a raw_spinlock_t in unwind
    Date
    From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

    [ 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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm/kernel/unwind.c | 14 +++++++-------
    1 file changed, 7 insertions(+), 7 deletions(-)

    diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
    index 0bee233fef9a..314cfb232a63 100644
    --- a/arch/arm/kernel/unwind.c
    +++ b/arch/arm/kernel/unwind.c
    @@ -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);
    }
    --
    2.19.1
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