Re: Deadlock when using crypto API for block devices

From: Herbert Xu
Date: Fri Aug 24 2018 - 09:21:54 EST

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?

Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
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