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

[Jens Axboe]

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@xxxxxxxxx>
> ---
> 
> 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