linux-kernel - Re: block: sleeping in atomic warnings

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Message-ID: <CAHk-=wgmZDqCOynfiH4NFoL50f4+yUjxjp0sCaWS=xUmy731CQ@mail.gmail.com>
Date:   Tue, 7 Feb 2023 10:24:45 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     Dan Carpenter <error27@...il.com>, linux-block@...r.kernel.org,
        Julia Lawall <julia.lawall@...ia.fr>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Hongchen Zhang <zhanghongchen@...ngson.cn>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Christian Brauner (Microsoft)" <brauner@...nel.org>,
        David Howells <dhowells@...hat.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        maobibo <maobibo@...ngson.cn>,
        Matthew Wilcox <willy@...radead.org>,
        Sedat Dilek <sedat.dilek@...il.com>
Subject: Re: block: sleeping in atomic warnings

On Tue, Feb 7, 2023 at 9:53 AM Eric Biggers <ebiggers@...nel.org> wrote:
>
> It's a false positive.  See the comment above fscrypt_destroy_keyring()

Hmm. Ok. Unfortunate.

>  If the filesystem has not been mounted, then the call from __put_super()
> is needed, but blk_crypto_evict_key() can never be executed in that case.

It's not all that clear that some *other* error might not have
happened to keep the mount from actually succeeding, but after the
keys have been instantiated?

IOW, what's the thing that makes "blk_crypto_evict_key() can never be
executed in that case" be obvious?

I think _that_ is what might want a comment, about how we always call
generic_shutdown_super() before the last put_super() happens.

It does seem like Dan's automated checks could be useful, but if
there's no sane way to avoid the false positives, it's always going to
be a lot of noise ;(

           Linus