Messages in this thread Patch in this message | | | From | Thomas Gleixner <> | Subject | x86/i8259: Use printk_deferred() to prevent deadlock | Date | Wed, 29 Jul 2020 10:53:28 +0200 |
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0day reported a possible circular locking dependency:
Chain exists of: &irq_desc_lock_class --> console_owner --> &port_lock_key
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&port_lock_key); lock(console_owner); lock(&port_lock_key); lock(&irq_desc_lock_class);
The reason for this is a printk() in the i8259 interrupt chip driver which is invoked with the irq descriptor lock held, which reverses the lock operations vs. printk() from arbitrary contexts.
Switch the printk() to printk_deferred() to avoid that.
Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org --- arch/x86/kernel/i8259.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/i8259.c +++ b/arch/x86/kernel/i8259.c @@ -207,7 +207,7 @@ static void mask_and_ack_8259A(struct ir * lets ACK and report it. [once per IRQ] */ if (!(spurious_irq_mask & irqmask)) { - printk(KERN_DEBUG + printk_deferred(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq); spurious_irq_mask |= irqmask; }
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