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From: Michael Ellerman <mpe@ellerman•id.au>
To: Bart Van Assche <Bart.VanAssche@wdc•com>,
	"linuxppc-dev@lists•ozlabs.org" <linuxppc-dev@lists•ozlabs.org>,
	"abdhalee@linux•vnet.ibm.com" <abdhalee@linux•vnet.ibm.com>
Cc: "sachinp@linux•vnet.ibm.com" <sachinp@linux•vnet.ibm.com>,
	"sfr@canb•auug.org.au" <sfr@canb•auug.org.au>,
	"hare@suse•com" <hare@suse•com>,
	"martin.petersen@oracle•com" <martin.petersen@oracle•com>,
	"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>,
	"linux-next@vger•kernel.org" <linux-next@vger•kernel.org>,
	"hch@lst•de" <hch@lst•de>
Subject: Re: [BUG][bisected 270065e] linux-next fails to boot on powerpc
Date: Thu, 17 Aug 2017 17:06:38 +1000	[thread overview]
Message-ID: <87d17usmf5.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <1502915146.2421.13.camel@wdc.com>

Bart Van Assche <Bart.VanAssche@wdc•com> writes:

> On Wed, 2017-08-16 at 22:30 +0530, Abdul Haleem wrote:
>> As of next-20170809, linux-next on powerpc boot hung with below trace
>> message.
>> [ ... ]
>> System booted fine when the below commit is reverted: 
>
> Hello Abdul,
>
> Can you check whether applying the following commit on top of next-20170809
> fixes this regression:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git/commit/?h=4.13/scsi-fixes&id=b0e17a9b0df29590c45dfb296f541270a5941f41

That's already in next-20170816, which still exhibits the bug.

We know that reverting it fixes the bug, but I can also fix it by doing
a partial revert, ie:

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 582769116f66..95f1428c5bc9 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -190,7 +190,9 @@ static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
 	 */
 	cmd->result = 0;
 	if (q->mq_ops) {
-		scsi_mq_requeue_cmd(cmd);
+		struct scsi_device *sdev = cmd->device;
+		blk_mq_requeue_request(cmd->request, true);
+		put_device(&sdev->sdev_gendev);
 		return;
 	}
 	spin_lock_irqsave(q->queue_lock, flags);


That's basically inlining the old version of scsi_mq_requeue_cmd() at
the other call site in __scsi_queue_insert().

Now I guess that was fairly obvious, if you look closely at the commit,
and the fact that we're not hitting the WARN_ON() you added.

Anyway let me know if there's anything else I can try.

cheers

      reply	other threads:[~2017-08-17  7:06 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-16 17:00 [BUG][bisected 270065e] linux-next fails to boot on powerpc Abdul Haleem
2017-08-16 17:21 ` Bart Van Assche
2017-08-16 23:18   ` Brian King
2017-08-17 15:52     ` Bart Van Assche
2017-08-18 21:04       ` Brian King
2017-08-18 21:17         ` [PATCH] ipr: Set no_report_opcodes for RAID arrays Brian King
2017-08-21 20:22           ` Martin K. Petersen
2017-08-18 21:41         ` [BUG][bisected 270065e] linux-next fails to boot on powerpc Bart Van Assche
2017-08-18 21:57           ` Brian King
2017-08-18 22:13             ` Bart Van Assche
2017-08-21 22:11               ` [PATCH 0/2] Allow scsi_prep_fn to occur for retried commands Brian King
2017-08-21 22:13                 ` [PATCH 1/2] scsi: Move scsi_cmd->jiffies_at_alloc initialization to allocation time Brian King
2017-08-21 22:16                   ` Brian King
2017-08-21 22:40                   ` [PATCHv2 " Brian King
2017-08-22  6:51                   ` [PATCH " hch
2017-08-21 22:14                 ` [PATCH 2/2] scsi: Preserve retry counter through scsi_prep_fn Brian King
2017-08-22  6:51                   ` hch
2017-08-22  6:42                 ` [PATCH 0/2] Allow scsi_prep_fn to occur for retried commands Abdul Haleem
2017-08-21 20:27             ` [BUG][bisected 270065e] linux-next fails to boot on powerpc Martin K. Petersen
2017-08-17  1:33   ` Michael Ellerman
2017-08-16 20:25 ` Bart Van Assche
2017-08-17  7:06   ` Michael Ellerman [this message]

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