From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49uVzOGOrxO1VSxTKp1I/d/1aFP1ZY7R9A41avZhpoglIumQRuVS0htaRzcekU2Fmjavj0e ARC-Seal: i=1; a=rsa-sha256; t=1524653067; cv=none; d=google.com; s=arc-20160816; b=t6VYY+KHz4oJ7rZMwS07aHmLVFBAaEne3uv4MSxGyNtXnZqXB93q278bMHyP6pPGsh RRAK9tYN0/Y6xtzA8nh8NoFWmAIryc3atNCbH58aAB9dl/ZxErvBJs9Dp/+W6do6o9cq RwRPipyM7k5SCg03UKIgSiQnyeP/qgZG/4BNeHGRvTGXxwAxjRD26ml/m2O2VpcUUGIT hx80aZjjVUj2jNn5krE/lqKyER0nRB5ifozQIrlx++FGQeOFxvcQR/7VyFp7Vt/X2dSa e1PNhdrG0Ico06jYuSwIIMwa48wvMAikV4MTXn6vJ5xBVXFmIHUhIqc8xuVZ6sxe1QSK aplQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=wRJ7ww7S3PUiDKRPI/3M12e88T3SqTgGjX9KNElwF6A=; b=BnL4ko3sAQ8HANS7BVov6kwYeZz4xX7MZjKyNdvLzoTNbY9VYYx5fJ04q3xyEQBaUJ aywOYC6ddCOoW8HIgukUnvwMWXpi9dVCQx20wTBT7lIGwM7V0uDOfhyX9CRv3AeVcdbc fKmsoxjbNMEXMbwq9qCy7O70uJzDasPpEoY4/O04euPg6qgvvIAtFulQHJFF4ezO3k2c 5c8sgiwBVuw3Lv9SzYZVfBV/ue1pGqj9Uv2TIXd/qSFGmA0EyK0Qi85flBCYOtNpfPUx ZdrUNNIPF3pVaDewRQmerdZzppgJCGoCD9u8OYLSwc32VEkBzhvAEyDSz+OXXlfeIek0 kfMA== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mark Salter , Marc Zyngier , Sasha Levin Subject: [PATCH 4.14 171/183] irqchip/gic-v3: Change pr_debug message to pr_devel Date: Wed, 25 Apr 2018 12:36:31 +0200 Message-Id: <20180425103249.384808464@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180425103242.532713678@linuxfoundation.org> References: <20180425103242.532713678@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1598714615040749175?= X-GMAIL-MSGID: =?utf-8?q?1598714615040749175?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Salter [ Upstream commit b6dd4d83dc2f78cebc9a7e6e7e4bc2be4d29b94d ] The pr_debug() in gic-v3 gic_send_sgi() can trigger a circular locking warning: GICv3: CPU10: ICC_SGI1R_EL1 5000400 ====================================================== WARNING: possible circular locking dependency detected 4.15.0+ #1 Tainted: G W ------------------------------------------------------ dynamic_debug01/1873 is trying to acquire lock: ((console_sem).lock){-...}, at: [<0000000099c891ec>] down_trylock+0x20/0x4c but task is already holding lock: (&rq->lock){-.-.}, at: [<00000000842e1587>] __task_rq_lock+0x54/0xdc which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&rq->lock){-.-.}: __lock_acquire+0x3b4/0x6e0 lock_acquire+0xf4/0x2a8 _raw_spin_lock+0x4c/0x60 task_fork_fair+0x3c/0x148 sched_fork+0x10c/0x214 copy_process.isra.32.part.33+0x4e8/0x14f0 _do_fork+0xe8/0x78c kernel_thread+0x48/0x54 rest_init+0x34/0x2a4 start_kernel+0x45c/0x488 -> #1 (&p->pi_lock){-.-.}: __lock_acquire+0x3b4/0x6e0 lock_acquire+0xf4/0x2a8 _raw_spin_lock_irqsave+0x58/0x70 try_to_wake_up+0x48/0x600 wake_up_process+0x28/0x34 __up.isra.0+0x60/0x6c up+0x60/0x68 __up_console_sem+0x4c/0x7c console_unlock+0x328/0x634 vprintk_emit+0x25c/0x390 dev_vprintk_emit+0xc4/0x1fc dev_printk_emit+0x88/0xa8 __dev_printk+0x58/0x9c _dev_info+0x84/0xa8 usb_new_device+0x100/0x474 hub_port_connect+0x280/0x92c hub_event+0x740/0xa84 process_one_work+0x240/0x70c worker_thread+0x60/0x400 kthread+0x110/0x13c ret_from_fork+0x10/0x18 -> #0 ((console_sem).lock){-...}: validate_chain.isra.34+0x6e4/0xa20 __lock_acquire+0x3b4/0x6e0 lock_acquire+0xf4/0x2a8 _raw_spin_lock_irqsave+0x58/0x70 down_trylock+0x20/0x4c __down_trylock_console_sem+0x3c/0x9c console_trylock+0x20/0xb0 vprintk_emit+0x254/0x390 vprintk_default+0x58/0x90 vprintk_func+0xbc/0x164 printk+0x80/0xa0 __dynamic_pr_debug+0x84/0xac gic_raise_softirq+0x184/0x18c smp_cross_call+0xac/0x218 smp_send_reschedule+0x3c/0x48 resched_curr+0x60/0x9c check_preempt_curr+0x70/0xdc wake_up_new_task+0x310/0x470 _do_fork+0x188/0x78c SyS_clone+0x44/0x50 __sys_trace_return+0x0/0x4 other info that might help us debug this: Chain exists of: (console_sem).lock --> &p->pi_lock --> &rq->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&rq->lock); lock(&p->pi_lock); lock(&rq->lock); lock((console_sem).lock); *** DEADLOCK *** 2 locks held by dynamic_debug01/1873: #0: (&p->pi_lock){-.-.}, at: [<000000001366df53>] wake_up_new_task+0x40/0x470 #1: (&rq->lock){-.-.}, at: [<00000000842e1587>] __task_rq_lock+0x54/0xdc stack backtrace: CPU: 10 PID: 1873 Comm: dynamic_debug01 Tainted: G W 4.15.0+ #1 Hardware name: GIGABYTE R120-T34-00/MT30-GS2-00, BIOS T48 10/02/2017 Call trace: dump_backtrace+0x0/0x188 show_stack+0x24/0x2c dump_stack+0xa4/0xe0 print_circular_bug.isra.31+0x29c/0x2b8 check_prev_add.constprop.39+0x6c8/0x6dc validate_chain.isra.34+0x6e4/0xa20 __lock_acquire+0x3b4/0x6e0 lock_acquire+0xf4/0x2a8 _raw_spin_lock_irqsave+0x58/0x70 down_trylock+0x20/0x4c __down_trylock_console_sem+0x3c/0x9c console_trylock+0x20/0xb0 vprintk_emit+0x254/0x390 vprintk_default+0x58/0x90 vprintk_func+0xbc/0x164 printk+0x80/0xa0 __dynamic_pr_debug+0x84/0xac gic_raise_softirq+0x184/0x18c smp_cross_call+0xac/0x218 smp_send_reschedule+0x3c/0x48 resched_curr+0x60/0x9c check_preempt_curr+0x70/0xdc wake_up_new_task+0x310/0x470 _do_fork+0x188/0x78c SyS_clone+0x44/0x50 __sys_trace_return+0x0/0x4 GICv3: CPU0: ICC_SGI1R_EL1 12000 This could be fixed with printk_deferred() but that might lessen its usefulness for debugging. So change it to pr_devel to keep it out of production kernels. Developers working on gic-v3 can enable it as needed in their kernels. Signed-off-by: Mark Salter Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/irqchip/irq-gic-v3.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/irqchip/irq-gic-v3.c +++ b/drivers/irqchip/irq-gic-v3.c @@ -645,7 +645,7 @@ static void gic_send_sgi(u64 cluster_id, MPIDR_TO_SGI_AFFINITY(cluster_id, 1) | tlist << ICC_SGI1R_TARGET_LIST_SHIFT); - pr_debug("CPU%d: ICC_SGI1R_EL1 %llx\n", smp_processor_id(), val); + pr_devel("CPU%d: ICC_SGI1R_EL1 %llx\n", smp_processor_id(), val); gic_write_sgi1r(val); }