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

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Date:   Tue, 5 Jun 2018 17:08:34 +0200
From:   David Sterba <dsterba@...e.cz>
To:     dsterba@...e.cz, Jens Axboe <axboe@...nel.dk>,
        Kent Overstreet <kent.overstreet@...il.com>,
        torvalds@...ux-foundation.org, snitzer@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dm: Use kzalloc for all structs with embedded
 biosets/mempools

On Tue, Jun 05, 2018 at 04:35:07PM +0200, 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.

Tested-by: David Sterba <dsterba@...e.com>

on targets snapshot and thin.