linux-kernel - Re: [PATCH v7] KEYS: Add a list for unreferenced keys

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Message-ID: <Z_O1v8awuTeJ9qfS@kernel.org>
Date: Mon, 7 Apr 2025 14:23:43 +0300
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: keyrings@...r.kernel.org, Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>,
	stable@...r.kernel.org, David Howells <dhowells@...hat.com>,
	Lukas Wunner <lukas@...ner.de>,
	Ignat Korchagin <ignat@...udflare.com>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
	Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Mimi Zohar <zohar@...ux.ibm.com>, linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH v7] KEYS: Add a list for unreferenced keys

On Mon, Apr 07, 2025 at 12:25:11PM +0200, Marek Szyprowski wrote:
> On 07.04.2025 04:39, Jarkko Sakkinen wrote:
> > From: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
> >
> > Add an isolated list of unreferenced keys to be queued for deletion, and
> > try to pin the keys in the garbage collector before processing anything.
> > Skip unpinnable keys.
> >
> > Use this list for blocking the reaping process during the teardown:
> >
> > 1. First off, the keys added to `keys_graveyard` are snapshotted, and the
> >     list is flushed. This the very last step in `key_put()`.
> > 2. `key_put()` reaches zero. This will mark key as busy for the garbage
> >     collector.
> > 3. `key_garbage_collector()` will try to increase refcount, which won't go
> >     above zero. Whenever this happens, the key will be skipped.
> >
> > Cc: stable@...r.kernel.org # v6.1+ Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...nsys.com>
> This patch landed in today's linux-next as commit b0d023797e3e ("keys: 
> Add a list for unreferenced keys"). In my tests I found that it triggers 
> the following lockdep issue:
> 
> ================================
> WARNING: inconsistent lock state
> 6.15.0-rc1-next-20250407 #15630 Not tainted
> --------------------------------
> inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
> ksoftirqd/3/32 [HC0[0]:SC1[1]:HE1:SE0] takes:
> c13fdd68 (key_serial_lock){+.?.}-{2:2}, at: key_put+0x74/0x128
> {SOFTIRQ-ON-W} state was registered at:
>    lock_acquire+0x134/0x384
>    _raw_spin_lock+0x38/0x48
>    key_alloc+0x2fc/0x4d8
>    keyring_alloc+0x40/0x90
>    system_trusted_keyring_init+0x50/0x7c
>    do_one_initcall+0x68/0x314
>    kernel_init_freeable+0x1c0/0x224
>    kernel_init+0x1c/0x12c
>    ret_from_fork+0x14/0x28
> irq event stamp: 234
> hardirqs last  enabled at (234): [<c0cb7060>] 
> _raw_spin_unlock_irqrestore+0x5c/0x60
> hardirqs last disabled at (233): [<c0cb6dd0>] 
> _raw_spin_lock_irqsave+0x64/0x68
> softirqs last  enabled at (42): [<c013bcd8>] handle_softirqs+0x328/0x520
> softirqs last disabled at (47): [<c013bf10>] run_ksoftirqd+0x40/0x68

OK what went to -next went there by accident and has been removed,
sorry. I think it was like the very first version of this patch.

Thanks for informing anyhow!

BR, Jarkko