linux-kernel - Re: [PATCH v7 9/9] block: Avoid deadlocks with bio allocation by stacking drivers

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Message-ID: <20120904193949.GC2603@redhat.com>
Date:	Tue, 4 Sep 2012 15:39:49 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Mikulas Patocka <mpatocka@...hat.com>
Cc:	Kent Overstreet <koverstreet@...gle.com>,
	linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
	dm-devel@...hat.com, tj@...nel.org, bharrosh@...asas.com,
	Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH v7 9/9] block: Avoid deadlocks with bio allocation by
 stacking drivers

On Tue, Sep 04, 2012 at 03:26:19PM -0400, Mikulas Patocka wrote:

[..]
> BTW. can these new-style timerless plugs introduce deadlocks too? What 
> happens when some bios are indefinitely delayed because their requests are 
> held in a plug and a mempool runs out?

I think they will not deadlock because these on stack bios/requests are
flushed/dispatched when process schedules out. So if a submitter blocks
on a mempool, it will be scheduled out and requests on plug will be 
dispatched.

Thanks
Vivek
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