From: Hannes Reinecke <hare@suse.de>
To: Junichi Nomura <j-nomura@ce.jp.nec.com>
Cc: "dm-devel@redhat.com" <dm-devel@redhat.com>,
Mike Snitzer <snitzer@redhat.com>,
Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH 4/7] dm mpath: remove process_queued_ios()
Date: Tue, 04 Feb 2014 12:31:29 +0100 [thread overview]
Message-ID: <52F0CF91.60302@suse.de> (raw)
In-Reply-To: <11AF7C027C4C02408624617A498607840105F76A@BPXM12GP.gisp.nec.co.jp>
On 02/04/2014 12:26 PM, Junichi Nomura wrote:
> On 02/04/14 19:54, Hannes Reinecke wrote:
>> We only need to take care to add a small delay when calling
>> __pg_init_all_paths() to move processing off to a workqueue; otherwise
>> pg_init_done() might end up calling scsi_dh_activate() directly, which
>> might use non-atomic memory allocations or issue I/O.
>
> Hi Hannes,
>
> could you tell me how "might end up calling scsi_dh_active()" happens?
>
> queue_delayed_work()
> queue_delayed_work_on()
> __queue_delayed_work()
> if (!delay)
> __queue_work()
> get_work_pool()
> insert_work()
> set_work_pwq()
> get_pwq()
> if (__need_more_worker())
> wake_up_worker()
>
> queue_work() doesn't execute the work itself.
>
> What am I missing?
>
As mentioned, I stumbled across the same issue when developing the
asynchronous SCSI aborts. I'll see to have it recreated with this
patchset.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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next prev parent reply other threads:[~2014-02-04 11:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 10:54 [PATCHv7 0/7] dm-multipath: push back requests instead of queueing Hannes Reinecke
2014-02-04 10:54 ` [PATCH 1/7] dm mpath: do not call pg_init when it is already running Hannes Reinecke
2014-02-04 10:54 ` [PATCH 2/7] dm table: add dm_table_run_md_queue_async Hannes Reinecke
2014-02-04 10:54 ` [PATCH 3/7] dm mpath: push back requests instead of queueing Hannes Reinecke
2014-02-04 10:54 ` [PATCH 4/7] dm mpath: remove process_queued_ios() Hannes Reinecke
2014-02-04 11:26 ` Junichi Nomura
2014-02-04 11:31 ` Hannes Reinecke [this message]
2014-02-10 13:30 ` Mike Snitzer
2014-02-11 9:46 ` Hannes Reinecke
2014-02-11 15:55 ` Mike Snitzer
2014-02-11 18:03 ` Hannes Reinecke
2014-02-11 16:29 ` Mike Snitzer
2014-02-12 2:37 ` Junichi Nomura
2014-02-04 10:54 ` [PATCH 5/7] dm mpath: reduce memory pressure when requeuing Hannes Reinecke
2014-02-04 10:54 ` [PATCH 6/7] dm mpath: remove map_io() Hannes Reinecke
2014-02-04 10:54 ` [PATCH 7/7] dm mpath: remove extra nesting in map function Hannes Reinecke
-- strict thread matches above, loose matches on Subject: below --
2014-02-03 20:28 [PATCH v6 0/7] dm-multipath: push back requests instead of queueing Mike Snitzer
2014-02-03 20:28 ` [PATCH 4/7] dm mpath: remove process_queued_ios() Mike Snitzer
2014-02-04 3:24 ` Junichi Nomura
2014-02-04 8:18 ` Hannes Reinecke
2014-02-04 8:55 ` Junichi Nomura
2014-02-04 9:08 ` Hannes Reinecke
2014-02-04 9:27 ` Junichi Nomura
2014-02-04 9:45 ` Hannes Reinecke
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