On Tue, Jun 05 2018 at 10:22P -0400, Jens Axboe <[email protected]> wrote:
> 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 <[email protected]> > > --- > > > > 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? Yes, looks good. >From the start of revisiting these changes last week, Kent and I discussed whether it was safe to call mempool_exit() even if mempool_init() failed or was never called. He advised that it was so long as the containing structure was zeroed. But I forgot to audit that aspect. So this was an oversight by both of us. DM core uses kvzalloc_node for struct mapped_device and cache, crypt, integrity, verity-fec and zoned targets are already using kzalloc as needed. Acked-by: Mike Snitzer <[email protected]>
