linux-kernel - Re: [PATCH V4 10/12] block: call __bio_free in bio

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Message-ID: <20170628214249.z42lypwtgzgdzh62@kernel.org>
Date:   Wed, 28 Jun 2017 14:42:49 -0700
From:   Shaohua Li <shli@...nel.org>
To:     Christoph Hellwig <hch@....de>
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        tj@...nel.org, gregkh@...uxfoundation.org, axboe@...com,
        rostedt@...dmis.org, lizefan@...wei.com, Kernel-team@...com,
        Shaohua Li <shli@...com>
Subject: Re: [PATCH V4 10/12] block: call __bio_free in bio_endio

On Wed, Jun 28, 2017 at 11:29:08PM +0200, Christoph Hellwig wrote:
> On Wed, Jun 28, 2017 at 09:30:00AM -0700, Shaohua Li wrote:
> > From: Shaohua Li <shli@...com>
> > 
> > bio_free isn't a good place to free cgroup/integrity info. There are a
> > lot of cases bio is allocated in special way (for example, in stack) and
> > never gets called by bio_put hence bio_free, we are leaking memory. This
> > patch moves the free to bio endio, which should be called anyway. The
> > __bio_free call in bio_free is kept, in case the bio never gets called
> > bio endio.
> > 
> > This assumes ->bi_end_io() doesn't access cgroup/integrity info, which
> > seems true in my audit. Otherwise, we probably must add a flag to
> > distinguish if bio will be called by bio_put.
> 
> bio_integrity_endio -> bio_integrity_verify_fn -> bio_integrity_process
> access the integrity data, so I don't think this works as-is.

oh, I probably missed the integrity endio. could we let bio_integrity_verify_fn
free integrity info and and bio_endio free cgroup info?