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Subject: Re: [PATCH] dm: Use kzalloc for all structs with embedded
 biosets/mempools
To:     dsterba@suse.cz, Kent Overstreet <kent.overstreet@gmail.com>,
        torvalds@linux-foundation.org, snitzer@redhat.com,
        linux-kernel@vger.kernel.org
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 <20180605143507.2o3qm4r6euvyhe5g@twin.jikos.cz>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <8a4b20a3-899d-3317-407e-a6a2029d31b0@kernel.dk>
Date:   Tue, 5 Jun 2018 08:42:03 -0600
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On 6/5/18 8:35 AM, David Sterba wrote:
> On Tue, Jun 05, 2018 at 08:22:22AM -0600, Jens Axboe wrote:
>>> 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.
> 
> eg. fstests/generic/081 crashes (trace below), no KASAN, PAGE_POISONING=y,
> PAGE_POISONING_NO_SANITY=y.
> 
>> I can queue this up and ship it later today. Mike, you want to review
>> this one?
> 
> Would be great to push that soon. The fstests build on several DM targets, the
> crashes lead to many test failures. I'm going to test the kzalloc fix now.

For sure, it should go asap.

-- 
Jens Axboe