[dm-devel] Deadlock when using crypto API for block devices

[Herbert Xu]

On Fri, Aug 24, 2018 at 09:00:00AM -0400, Mikulas Patocka wrote:
>
> BTW. gcmaes_crypt_by_sg also contains GFP_ATOMIC and -ENOMEM, behind a 
> pretty complex condition. Do you mean that this condition is part of the 
> contract that the crypto API provides?

This is an implementation defect.  I think for this case we should
fall back to software GCM if the accelerated version fails.

> Should "req->src->offset + req->src->length < PAGE_SIZE" use "<=" instead? 
> Because if the data ends up at page boundary, it will use the atomic 
> allocation that can fail.

This condition does look strange.  It's introduced by the commit
e845520707f85c539ce04bb73c6070e9441480be.   Dave, what exactly is
it meant to do?

Thanks,
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
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