Re: [PATCH] block: fix memory leak in bio_clone()

From: Martin K. Petersen
Date: Mon Mar 09 2009 - 12:10:55 EST


>>>>> "Jens" == Jens Axboe <jens.axboe@xxxxxxxxxx> 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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