linux-kernel - Re: [PATCH] block: fix memory leak in bio

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Message-ID: <yq1prgqy8wc.fsf@sermon.lab.mkp.net>
Date:	Mon, 09 Mar 2009 12:10:27 -0400
From:	"Martin K. Petersen" <martin.petersen@...cle.com>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	Li Zefan <lizf@...fujitsu.com>,
	LKML <linux-kernel@...r.kernel.org>, martin.petersen@...cle.com
Subject: Re: [PATCH] block: fix memory leak in bio_clone()

>>>>> "Jens" == Jens Axboe <jens.axboe@...cle.com> writes:

Jens> So the leak will not occur, but it does mean that it isn't
Jens> honoring the gfp_mask passed in to bio_clone(), which is the first
Jens> bug.

bio_integrity_clone() had no mask because all callers of it used
GFP_NOIO explicitly.

But as you now recall there is a patch queued that adds the mask :)

Jens> The second bug is that it should be using its own bioset, as it is
Jens> illegal to do multiple __GFP_WAIT allocations on a single mempool
Jens> and always expect progress.

So how do you propose I go about this?

The original intent was to contain all the integrity blah inside the
bio_set to make it completely transparent to the caller.  That's why the
bip mempool is hanging off of the bio_set.  But obviously two bvecs are
needed per bio, one to describe data and to describe the integrity
buffer.

Having two bvec mempools per bio_set seems icky.  I guess what you are
suggesting is that we could have a dedicated bio_integrity_set akin to
the bio_split_pool.  That removes the caller's option of passing a
dedicated bio_set to the clone command, though.  Will that have forward
progress implications for stacking drivers?

-- 
Martin K. Petersen	Oracle Linux Engineering
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