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From:   Ming Lei <tom.leiming@gmail.com>
Date:   Fri, 17 Jul 2020 22:23:12 +0800
Message-ID: <CACVXFVNmU5MLO75f5QBpeBtBVqBCJ-oYp9HV_4LBBGZtFS9w_w@mail.gmail.com>
Subject: Re: [PATCH] scsi: core: run queue in case of IO queueing failure
To:     Ming Lei <ming.lei@redhat.com>
Cc:     James Bottomley <James.Bottomley@hansenpartnership.com>,
        Linux SCSI List <linux-scsi@vger.kernel.org>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        linux-block <linux-block@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Tue, Jul 14, 2020 at 8:38 AM Ming Lei <ming.lei@redhat.com> wrote:
>
> On Wed, Jul 08, 2020 at 09:14:05PM +0800, Ming Lei wrote:
> > IO requests may be held in scheduler queue because of resource contention.
> > However, not like normal completion, when queueing request failed, we don't
> > ask block layer to queue these requests, so IO hang[1] is caused.
> >
> > Fix this issue by run queue when IO request failure happens.
> >
> > [1] IO hang log by running heavy IO with removing scsi device
> >
> > [   39.054963] scsi 13:0:0:0: rejecting I/O to dead device
> > [   39.058700] scsi 13:0:0:0: rejecting I/O to dead device
> > [   39.087855] sd 13:0:0:1: [sdd] Synchronizing SCSI cache
> > [   39.088909] scsi 13:0:0:1: rejecting I/O to dead device
> > [   39.095351] scsi 13:0:0:1: rejecting I/O to dead device
> > [   39.096962] scsi 13:0:0:1: rejecting I/O to dead device
> > [  247.021859] INFO: task scsi-stress-rem:813 blocked for more than 122 seconds.
> > [  247.023258]       Not tainted 5.8.0-rc2 #8
> > [  247.024069] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> > [  247.025331] scsi-stress-rem D    0   813    802 0x00004000
> > [  247.025334] Call Trace:
> > [  247.025354]  __schedule+0x504/0x55f
> > [  247.027987]  schedule+0x72/0xa8
> > [  247.027991]  blk_mq_freeze_queue_wait+0x63/0x8c
> > [  247.027994]  ? do_wait_intr_irq+0x7a/0x7a
> > [  247.027996]  blk_cleanup_queue+0x4b/0xc9
> > [  247.028000]  __scsi_remove_device+0xf6/0x14e
> > [  247.028002]  scsi_remove_device+0x21/0x2b
> > [  247.029037]  sdev_store_delete+0x58/0x7c
> > [  247.029041]  kernfs_fop_write+0x10d/0x14f
> > [  247.031281]  vfs_write+0xa2/0xdf
> > [  247.032670]  ksys_write+0x6b/0xb3
> > [  247.032673]  do_syscall_64+0x56/0x82
> > [  247.034053]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > [  247.034059] RIP: 0033:0x7f69f39e9008
> > [  247.036330] Code: Bad RIP value.
> > [  247.036331] RSP: 002b:00007ffdd8116498 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
> > [  247.037613] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f69f39e9008
> > [  247.039714] RDX: 0000000000000002 RSI: 000055cde92a0ab0 RDI: 0000000000000001
> > [  247.039715] RBP: 000055cde92a0ab0 R08: 000000000000000a R09: 00007f69f3a79e80
> > [  247.039716] R10: 000000000000000a R11: 0000000000000246 R12: 00007f69f3abb780
> > [  247.039717] R13: 0000000000000002 R14: 00007f69f3ab6740 R15: 0000000000000002
> >
> > Cc: linux-block@vger.kernel.org
> > Cc: Christoph Hellwig <hch@lst.de>
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >  drivers/scsi/scsi_lib.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> > index 534b85e87c80..4d7fab9e8af9 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -1694,6 +1694,16 @@ static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
> >                */
> >               if (req->rq_flags & RQF_DONTPREP)
> >                       scsi_mq_uninit_cmd(cmd);
> > +
> > +             /*
> > +              * Requests may be held in block layer queue because of
> > +              * resource contention. We usually run queue in normal
> > +              * completion for queuing these requests again. Block layer
> > +              * will finish this failed request simply, run queue in case
> > +              * of IO queueing failure so that requests can get chance to
> > +              * be finished.
> > +              */
> > +             scsi_run_queue(q);
> >               break;
> >       }
> >       return ret;
>
> Hello Guys,
>
> Ping...

Ping again...


-- 
Ming Lei