From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: General protection fault with use_blk_mq=1. Date: Wed, 28 Mar 2018 21:22:47 -0600 Message-ID: <735c5d75-eacf-8ed2-ba9b-9ff4b0b5290d@kernel.dk> References: <7d8a9c62-7d3e-879c-5b5b-30707f04553e@aehallh.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: "Zephaniah E. Loss-Cutler-Hull" , "Zephaniah E. Loss-Cutler-Hull" , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org Cc: Paolo Valente List-Id: linux-scsi@vger.kernel.org On 3/28/18 9:13 PM, Zephaniah E. Loss-Cutler-Hull wrote: > On 03/28/2018 06:02 PM, Jens Axboe wrote: >> On 3/28/18 5:03 PM, Zephaniah E. Loss-Cutler-Hull wrote: >>> I am not subscribed to any of the lists on the To list here, please CC >>> me on any replies. >>> >>> I am encountering a fairly consistent crash anywhere from 15 minutes to >>> 12 hours after boot with scsi_mod.use_blk_mq=1 dm_mod.use_blk_mq=1> >>> The crash looks like: >>> > >>> >>> Looking through the code, I'd guess that this is dying inside >>> blkg_rwstat_add, which calls percpu_counter_add_batch, which is what RIP >>> is pointing at. >> >> Leaving the whole thing here for Paolo - it's crashing off insertion of >> a request coming out of SG_IO. Don't think we've seen this BFQ failure >> case before. >> >> You can mitigate this by switching the scsi-mq devices to mq-deadline >> instead. >> > > I'm thinking that I should also be able to mitigate it by disabling > CONFIG_DEBUG_BLK_CGROUP. > > That should remove that entire chunk of code. > > Of course, that won't help if this is actually a symptom of a bigger > problem. Yes, it's not a given that it will fully mask the issue at hand. But turning off BFQ has a much higher chance of working for you. This time actually CC'ing Paolo. -- Jens Axboe