linux-kernel - Re: dm-crypt with no_read_workqueue and no_write

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Message-ID: <20201223205642.GA19817@gondor.apana.org.au>
Date:   Thu, 24 Dec 2020 07:56:42 +1100
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
Cc:     Ignat Korchagin <ignat@...udflare.com>, agk@...hat.com,
        snitzer@...hat.com, dm-devel@...hat.com, dm-crypt@...ut.de,
        linux-kernel@...r.kernel.org, ebiggers@...nel.org,
        Damien.LeMoal@....com, mpatocka@...hat.com,
        kernel-team@...udflare.com, nobuto.murata@...onical.com,
        Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>, linux-btrfs@...r.kernel.org,
        linux-crypto <linux-crypto@...r.kernel.org>
Subject: Re: dm-crypt with no_read_workqueue and no_write_workqueue + btrfs
 scrub = BUG()

On Wed, Dec 23, 2020 at 04:37:34PM +0100, Maciej S. Szmigiero wrote:
> 
> It looks like to me that the skcipher API might not be safe to
> call from a softirq context, after all.

skcipher is safe to use in a softirq.  The problem is only in
dm-crypt where it tries to allocate memory with GFP_NOIO.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt