From: Hannes Reinecke <hare@suse.de>
To: Brian Bunker <brian@purestorage.com>
Cc: "Ewan D. Milne" <emilne@redhat.com>, linux-scsi@vger.kernel.org
Subject: Re: [PATCH 1/1] scsi: scsi_dh_alua: do not set h->sdev to NULL before removing the list entry
Date: Thu, 24 Sep 2020 12:42:43 +0200 [thread overview]
Message-ID: <ec422868-3c9d-f9de-5bed-14e9d6093ebb@suse.de> (raw)
In-Reply-To: <F861B128-F3AC-4928-9B9C-14DE921F70FD@purestorage.com>
On 9/24/20 12:21 AM, Brian Bunker wrote:
> We have tried with our patch here and it works. We have not tried with our patch at the
> customer site where they hit the crash. Since they hit the BUG_ON line which we
> can see in the logs we have, we expect that removing the race as we did
> would avoid the crash. We also remove the BUG_ON’s in our patch so it can’t hit
> the same crash. If there is another similar race a null pointer deference could still
> happen in our patch. I saw you had a patch to only use the value if the pointer is not
> null. That would also work to stop the crash, but it would hide the race where the
> BUG_ON was helpful in finding it.
>
> Trying our fix at the customer site for us would be more difficult since the operating
> system crash belongs to Oracle. That is why you see their patch for the same
> issue. Our interest in getting this fixed goes beyond this customer since more
> Linux vendors as they move forward in kernel version inherit this code, and
> we are reliant on ALUA. We hope to catch it here.
>
> Should I put together a patch with the h->sdev set to null removed from the
> detach function along the syncrhronize_rcu and removing the BUG_ON, or
> did you want me to diff against your checkin where you have already removed
> the BUG_ON?
>
No need, I already sent a patch attached to another mail to the oracle
folks.
Guess I'll be sending an 'official' patch now, seeing that I have
confirmation.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
prev parent reply other threads:[~2020-09-24 10:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 16:21 [PATCH 1/1] scsi: scsi_dh_alua: do not set h->sdev to NULL before removing the list entry Brian Bunker
2020-09-18 18:41 ` Ewan D. Milne
2020-09-18 22:07 ` Brian Bunker
2020-09-23 8:23 ` Hannes Reinecke
2020-09-23 22:21 ` Brian Bunker
2020-09-24 10:42 ` Hannes Reinecke [this message]
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