The following commit has been merged into the x86/urgent branch of tip: Commit-ID: bdd65589593edd79b6a12ce86b3b7a7c6dae5208 Gitweb: https://git.kernel.org/tip/bdd65589593edd79b6a12ce86b3b7a7c6dae5208 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Wed, 29 Jul 2020 10:53:28 +02:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Wed, 29 Jul 2020 16:27:16 +02:00 x86/i8259: Use printk_deferred() to prevent deadlock 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@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/87365abt2v.fsf@xxxxxxxxxxxxxxxxxxxxxxx --- arch/x86/kernel/i8259.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c index f3c7625..282b4ee 100644 --- a/arch/x86/kernel/i8259.c +++ b/arch/x86/kernel/i8259.c @@ -207,7 +207,7 @@ spurious_8259A_irq: * 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; }
