linux-kernel - Re: [PATCH] dm: Use kzalloc for all structs with embedded biosets/mempools

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Message-ID: <e78b0f9f-d4f9-d865-0727-5e1ed074928d@kernel.dk>
Date:   Tue, 5 Jun 2018 08:22:22 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Kent Overstreet <kent.overstreet@...il.com>,
        torvalds@...ux-foundation.org
Cc:     snitzer@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dm: Use kzalloc for all structs with embedded
 biosets/mempools

On 6/5/18 3:26 AM, Kent Overstreet wrote:
> mempool_init()/bioset_init() require that the mempools/biosets be zeroed
> first; they probably should not _require_ this, but not allocating those
> structs with kzalloc is a fairly nonsensical thing to do (calling
> mempool_exit()/bioset_exit() on an uninitialized mempool/bioset is legal
> and safe, but only works if said memory was zeroed.)
> 
> Signed-off-by: Kent Overstreet <kent.overstreet@...il.com>
> ---
> 
> Linus,
> 
> I fucked up majorly on the bioset/mempool conversion - I forgot to check that
> everything biosets/mempools were being embedded in was actually being zeroed on
> allocation. Device mapper currently explodes, you'll probably want to apply this
> patch post haste.
> 
> I have now done that auditing, for every single conversion - this patch fixes
> everything I found. There do not seem to be any incorrect ones outside of device
> mapper...
> 
> We'll probably want a second patch that either a) changes
> bioset_init()/mempool_init() to zero the passed in bioset/mempool first, or b)
> my preference, WARN() or BUG() if they're passed memory that isn't zeroed.

Odd, haven't seen a crash, but probably requires kasan or poisoning to
trigger anything? Mike's tree also had the changes, since they were based
on the block tree.

I can queue this up and ship it later today. Mike, you want to review
this one?

-- 
Jens Axboe