From: Laurence Oberman <loberman@redhat.com>
To: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Bart Van Assche <bvanassche@acm.org>,
Mike Snitzer <snitzer@redhat.com>,
dm-devel@redhat.com, linux-scsi@vger.kernel.org
Subject: Re: [dm-devel] dm-mq and end_clone_request()
Date: Mon, 8 Aug 2016 10:32:22 -0400 (EDT) [thread overview]
Message-ID: <1258167324.126153.1470666742190.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20160808134440.67am2eafnd4yrkxl@c203.arch.suse.de>
----- Original Message -----
> From: "Johannes Thumshirn" <jthumshirn@suse.de>
> To: "Laurence Oberman" <loberman@redhat.com>
> Cc: "Bart Van Assche" <bvanassche@acm.org>, "Mike Snitzer" <snitzer@redhat.com>, dm-devel@redhat.com,
> linux-scsi@vger.kernel.org
> Sent: Monday, August 8, 2016 9:44:40 AM
> Subject: Re: [dm-devel] dm-mq and end_clone_request()
>
> On Mon, Aug 08, 2016 at 08:45:59AM -0400, Laurence Oberman wrote:
> >
> >
> > ----- Original Message -----
> > > From: "Bart Van Assche" <bvanassche@acm.org>
> > > To: "Laurence Oberman" <loberman@redhat.com>
> > > Cc: "Mike Snitzer" <snitzer@redhat.com>, dm-devel@redhat.com,
> > > linux-scsi@vger.kernel.org
> > > Sent: Sunday, August 7, 2016 6:31:11 PM
> > > Subject: Re: [dm-devel] dm-mq and end_clone_request()
> > >
> > > On 08/06/16 07:47, Laurence Oberman wrote:
> > > > [66813.933246] Workqueue: srp_remove srp_remove_work [ib_srp]
> > > > [ ... ]
> > > > [66815.152051] [<ffffffff814ac790>] scsi_forget_host+0x60/0x70
> > > > [66815.183939] [<ffffffff814a0137>] scsi_remove_host+0x77/0x110
> > > > [66815.216152] [<ffffffffa0677be0>] srp_remove_work+0x90/0x200
> > > > [ib_srp]
> > > > [66815.253221] [<ffffffff810a2e72>] process_one_work+0x152/0x400
> > > > [66815.286221] [<ffffffff810a3765>] worker_thread+0x125/0x4b0
> > > > [66815.317313] [<ffffffff810a3640>] ? rescuer_thread+0x380/0x380
> > > > [66815.349770] [<ffffffff810a9298>] kthread+0xd8/0xf0
> > > > [66815.376082] [<ffffffff816c6b3f>] ret_from_fork+0x1f/0x40
> > > > [66815.404767] [<ffffffff810a91c0>] ? kthread_park+0x60/0x60
> > >
> > > Hello Laurence,
> > >
> > > This is a callstack I have not yet encountered myself during any test.
> > > Please provide the output of the following commands:
> > > $ gdb /lib/modules/$(uname -r)/build/vmlinux
> > > (gdb) list *(scsi_forget_host+0x60)
> > >
> > > Thanks,
> > >
> > > Bart.
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> > > the body of a message to majordomo@vger.kernel.org
> > > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > >
> > [loberman@jumptest1 linux]$ gdb vmlinux
> > GNU gdb (GDB) Red Hat Enterprise Linux 7.6.1-80.el7
> > Copyright (C) 2013 Free Software Foundation, Inc.
> > License GPLv3+: GNU GPL version 3 or later
> > <http://gnu.org/licenses/gpl.html>
> > This is free software: you are free to change and redistribute it.
> > There is NO WARRANTY, to the extent permitted by law. Type "show copying"
> > and "show warranty" for details.
> > This GDB was configured as "x86_64-redhat-linux-gnu".
> > For bug reporting instructions, please see:
> > <http://www.gnu.org/software/gdb/bugs/>...
> > Reading symbols from /home/loberman/bart/linux/vmlinux...done.
> > (gdb) list *(scsi_forget_host+0x60)
> > 0xffffffff814ac790 is in scsi_forget_host (drivers/scsi/scsi_scan.c:1895).
> > 1890 list_for_each_entry(sdev, &shost->__devices, siblings) {
> > 1891 if (sdev->sdev_state == SDEV_DEL)
> > 1892 continue;
> > 1893 spin_unlock_irqrestore(shost->host_lock, flags);
> > 1894 __scsi_remove_device(sdev);
> > 1895 goto restart;
> > 1896 }
> > 1897 spin_unlock_irqrestore(shost->host_lock, flags);
> > 1898 }
> > 1899
>
>
> So __scsi_remove_device() is also checking for sdev->sdev_state == SDEV_DEL
> and returns if so. If it would have the chance to do so the goto restart
> would
> be hit and we'd reatart the list traverse. The if in turn just continues and
> I've seen endless loops with this pattern (check the 40998193560 ->
> 90a88d6ef88edc -> f05795d3d771f30a7bd commit chain).
>
> Might want to give the below patch a shot?
>
>
> From fee838ebfea88b581994b3f855eab8da20b07fc9 Mon Sep 17 00:00:00 2001
> From: Johannes Thumshirn <jthumshirn@suse.de>
> Date: Mon, 8 Aug 2016 15:41:09 +0200
> Subject: [PATCH] scsi: restart full list search when re-encountering a
> deleted device
>
> __scsi_remove_device() already checks for reentrency with a deleted device,
> so there's no need to do it in scsi_forget_host() as well.
>
> Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
> ---
> drivers/scsi/scsi_scan.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index e0a78f5..1c5a4d6 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -1890,8 +1890,6 @@ void scsi_forget_host(struct Scsi_Host *shost)
> restart:
> spin_lock_irqsave(shost->host_lock, flags);
> list_for_each_entry(sdev, &shost->__devices, siblings) {
> - if (sdev->sdev_state == SDEV_DEL)
> - continue;
> spin_unlock_irqrestore(shost->host_lock, flags);
> __scsi_remove_device(sdev);
> goto restart;
> --
> 2.9.2
>
>
> --
> Johannes Thumshirn Storage
> jthumshirn@suse.de +49 911 74053 689
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: Felix Imendörffer, Jane Smithard, Graham Norton
> HRB 21284 (AG Nürnberg)
> Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850
> --
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
Johannes,
Thanks very much.
Regards
Laurence
next prev parent reply other threads:[~2016-08-08 14:32 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-19 22:57 dm-mq and end_clone_request() Bart Van Assche
2016-07-20 14:08 ` Mike Snitzer
2016-07-20 14:27 ` Mike Snitzer
2016-07-20 17:37 ` Bart Van Assche
2016-07-20 18:33 ` Mike Snitzer
2016-07-21 20:58 ` [dm-devel] " Bart Van Assche
2016-07-25 17:53 ` Mike Snitzer
2016-07-25 21:23 ` Mike Snitzer
2016-07-25 22:00 ` Bart Van Assche
2016-07-26 1:16 ` Mike Snitzer
2016-07-26 22:51 ` Bart Van Assche
2016-07-27 14:08 ` Mike Snitzer
2016-07-27 15:52 ` [dm-devel] " Benjamin Marzinski
2016-07-27 19:06 ` Bart Van Assche
2016-07-27 19:54 ` Mike Snitzer
2016-07-27 20:09 ` Mike Snitzer
2016-07-27 23:05 ` Bart Van Assche
2016-07-28 13:33 ` Mike Snitzer
2016-07-28 15:23 ` Bart Van Assche
2016-07-28 15:40 ` Mike Snitzer
2016-07-29 6:28 ` [dm-devel] " Hannes Reinecke
2016-07-26 6:02 ` Hannes Reinecke
2016-07-26 16:06 ` Mike Snitzer
[not found] ` <317679447.7168375.1469729769593.JavaMail.zimbra@redhat.com>
[not found] ` <6880321d-e14f-169b-d100-6e460dd9bd09@sandisk.com>
[not found] ` <1110327939.7305916.1469819453678.JavaMail.zimbra@redhat.com>
[not found] ` <a5c1a149-b1a2-b5a4-2207-bdaf32db3cbd@sandisk.com>
[not found] ` <757522831.7667712.1470059860543.JavaMail.zimbra@redhat.com>
[not found] ` <536022978.7668211.1470060125271.JavaMail.zimbra@redhat.com>
[not found] ` <931235537.7668834.1470060339483.JavaMail.zimbra@redhat.com>
[not found] ` <1264951811.7684268.1470065187014.JavaMail.zimbra@redhat.com>
[not found] ` <17da3ab0-233a-2cec-f921-bfd42c953ccc@sandisk.com>
2016-08-01 17:59 ` Mike Snitzer
2016-08-01 18:55 ` Bart Van Assche
2016-08-01 19:15 ` Mike Snitzer
2016-08-01 20:46 ` Mike Snitzer
2016-08-01 22:41 ` Bart Van Assche
2016-08-01 22:41 ` Bart Van Assche
2016-08-02 17:45 ` Mike Snitzer
2016-08-03 0:19 ` Bart Van Assche
2016-08-03 0:40 ` Mike Snitzer
2016-08-03 1:33 ` Laurence Oberman
2016-08-03 2:10 ` Mike Snitzer
2016-08-03 2:18 ` Laurence Oberman
2016-08-03 2:55 ` Laurence Oberman
2016-08-03 15:10 ` Laurence Oberman
2016-08-03 16:06 ` Bart Van Assche
2016-08-03 17:25 ` Laurence Oberman
2016-08-03 18:03 ` [dm-devel] " Laurence Oberman
2016-08-03 16:55 ` Bart Van Assche
2016-08-04 9:53 ` Hannes Reinecke
2016-08-04 10:09 ` Hannes Reinecke
2016-08-04 15:10 ` Mike Snitzer
2016-08-04 16:10 ` Mike Snitzer
2016-08-04 17:42 ` Bart Van Assche
2016-08-04 23:58 ` Mike Snitzer
2016-08-05 1:07 ` Laurence Oberman
2016-08-05 11:43 ` Laurence Oberman
2016-08-05 15:39 ` Laurence Oberman
2016-08-05 15:43 ` Bart Van Assche
2016-08-05 18:42 ` [dm-devel] " Bart Van Assche
2016-08-06 14:47 ` Laurence Oberman
2016-08-07 22:31 ` [dm-devel] " Bart Van Assche
2016-08-08 12:45 ` Laurence Oberman
2016-08-08 13:44 ` Johannes Thumshirn
2016-08-08 13:44 ` Johannes Thumshirn
2016-08-08 14:32 ` Laurence Oberman [this message]
2016-08-08 14:54 ` Bart Van Assche
2016-08-08 15:11 ` Bart Van Assche
2016-08-08 15:26 ` Laurence Oberman
2016-08-08 15:28 ` Bart Van Assche
2016-08-08 22:39 ` Bart Van Assche
2016-08-08 22:52 ` Laurence Oberman
2016-08-09 0:09 ` Laurence Oberman
2016-08-09 15:51 ` Bart Van Assche
2016-08-09 17:12 ` [dm-devel] " Laurence Oberman
2016-08-09 17:16 ` Bart Van Assche
2016-08-09 17:21 ` Laurence Oberman
2016-08-10 21:38 ` Laurence Oberman
2016-08-11 16:51 ` Laurence Oberman
2016-08-05 18:40 ` Bart Van Assche
2016-07-21 20:32 ` Mike Snitzer
2016-07-21 20:40 ` [dm-devel] " Bart Van Assche
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