----- Original Message ----- > From: "Johannes Thumshirn" <jthumshirn@xxxxxxx> > To: "Laurence Oberman" <loberman@xxxxxxxxxx> > Cc: "Bart Van Assche" <bvanassche@xxxxxxx>, "Mike Snitzer" <snitzer@xxxxxxxxxx>, dm-devel@xxxxxxxxxx, > linux-scsi@xxxxxxxxxxxxxxx > 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@xxxxxxx> > > > To: "Laurence Oberman" <loberman@xxxxxxxxxx> > > > Cc: "Mike Snitzer" <snitzer@xxxxxxxxxx>, dm-devel@xxxxxxxxxx, > > > linux-scsi@xxxxxxxxxxxxxxx > > > 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/$(uname -r)/build/vmlinux > > > (gdb) list *(scsi_forget_host+0x60) > > > > > > Thanks, > > > > > > Bart. > > > > > > -- > > > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > [loberman@jumptest1 linux]$ 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@xxxxxxx> > 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@xxxxxxx> > --- > 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@xxxxxxx +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@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Johannes, Thanks very much. Regards Laurence -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
