From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: [PATCH 2/3] block: Limit work processed in softirq context Date: Mon, 28 Mar 2016 14:49:46 -0700 Message-ID: <56F9A6FA.9040503@sandisk.com> References: <56F9A692.2090704@sandisk.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-by2on0069.outbound.protection.outlook.com ([207.46.100.69]:15850 "EHLO na01-by2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752252AbcC1Vtv (ORCPT ); Mon, 28 Mar 2016 17:49:51 -0400 In-Reply-To: <56F9A692.2090704@sandisk.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Jens Axboe Cc: Tejun Heo , James Bottomley , "Martin K. Petersen" , Mike Snitzer , "linux-scsi@vger.kernel.org" Avoid that complaints like the one below are reported against a debug kernel: NMI watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [disk11_0:2708] irq event stamp: 17120809 hardirqs last enabled at (17120808): [] _raw_spin_unlock_irqrestore+0x31/0x50 hardirqs last disabled at (17120809): [] 0xffff88046f223bd0 softirqs last enabled at (17120794): [] scst_check_blocked_dev+0x77/0x1c0 [scst] softirqs last disabled at (17120795): [] do_softirq_own_stack+0x1c/0x30 RIP: 0010:[] [] _raw_spin_unlock_irqrestore+0x33/0x50 Call Trace: [] free_debug_processing+0x270/0x3a0 [] __slab_free+0x17a/0x2c0 [] kmem_cache_free+0x1b4/0x1d0 [] mempool_free_slab+0x12/0x20 [] mempool_free+0x26/0x80 [] bio_free+0x49/0x60 [] bio_put+0x1e/0x30 [] end_clone_bio+0x21/0x70 [dm_mod] [] bio_endio+0x52/0x60 [] blk_update_request+0x7c/0x2a0 [] scsi_end_request+0x2e/0x1d0 [] scsi_io_completion+0xb4/0x610 [] scsi_finish_command+0xca/0x120 [] scsi_softirq_done+0x120/0x140 [] blk_done_softirq+0x76/0x90 [] __do_softirq+0x10f/0x230 [] do_softirq_own_stack+0x1c/0x30 Signed-off-by: Bart Van Assche --- block/blk-softirq.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/block/blk-softirq.c b/block/blk-softirq.c index 53b1737..d4d2fe4 100644 --- a/block/blk-softirq.c +++ b/block/blk-softirq.c @@ -21,10 +21,22 @@ static DEFINE_PER_CPU(struct list_head, blk_cpu_done); static void blk_done_softirq(struct softirq_action *h) { struct list_head *cpu_list, local_list; + struct request *e; + bool reraise = false; + int i = 0; local_irq_disable(); cpu_list = this_cpu_ptr(&blk_cpu_done); + list_for_each_entry(e, cpu_list, ipi_list) { + if (++i < 256) + continue; + list_cut_position(&local_list, cpu_list, &e->ipi_list); + reraise = true; + goto enable_irq; + } list_replace_init(cpu_list, &local_list); + +enable_irq: local_irq_enable(); while (!list_empty(&local_list)) { @@ -34,6 +46,14 @@ static void blk_done_softirq(struct softirq_action *h) list_del_init(&rq->ipi_list); rq->q->softirq_done_fn(rq); } + + if (!reraise) + return; + + local_irq_disable(); + if (!list_empty(cpu_list)) + raise_softirq_irqoff(BLOCK_SOFTIRQ); + local_irq_enable(); } #ifdef CONFIG_SMP -- 2.7.3