From: Petr Mladek <pmladek@suse.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kasan-dev@googlegroups.com,
John Ogness <john.ogness@linutronix.de>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: Re: [PATCH v2] mm/kfence: select random number before taking raw lock
Date: Thu, 9 Jun 2022 14:52:48 +0200 [thread overview]
Message-ID: <YqHtIGI7ueuI/ovx@alley> (raw)
In-Reply-To: <20220609123319.17576-1-Jason@zx2c4.com>
On Thu 2022-06-09 14:33:19, Jason A. Donenfeld wrote:
> The RNG uses vanilla spinlocks, not raw spinlocks, so kfence should pick
> its random numbers before taking its raw spinlocks. This also has the
> nice effect of doing less work inside the lock. It should fix a splat
> that Geert saw with CONFIG_PROVE_RAW_LOCK_NESTING:
>
> dump_backtrace.part.0+0x98/0xc0
> show_stack+0x14/0x28
> dump_stack_lvl+0xac/0xec
> dump_stack+0x14/0x2c
> __lock_acquire+0x388/0x10a0
> lock_acquire+0x190/0x2c0
> _raw_spin_lock_irqsave+0x6c/0x94
> crng_make_state+0x148/0x1e4
> _get_random_bytes.part.0+0x4c/0xe8
> get_random_u32+0x4c/0x140
> __kfence_alloc+0x460/0x5c4
> kmem_cache_alloc_trace+0x194/0x1dc
> __kthread_create_on_node+0x5c/0x1a8
> kthread_create_on_node+0x58/0x7c
> printk_start_kthread.part.0+0x34/0xa8
> printk_activate_kthreads+0x4c/0x54
> do_one_initcall+0xec/0x278
> kernel_init_freeable+0x11c/0x214
> kernel_init+0x24/0x124
> ret_from_fork+0x10/0x20
>
> Cc: John Ogness <john.ogness@linutronix.de>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Thanks a lot for fixing this. It is great to know that the printk
kthreads were not the culprit here ;-)
Best Regards,
Petr
next prev parent reply other threads:[~2022-06-09 12:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-09 12:17 [PATCH] " Jason A. Donenfeld
2022-06-09 12:27 ` Marco Elver
2022-06-09 12:29 ` Jason A. Donenfeld
2022-06-09 12:33 ` [PATCH v2] " Jason A. Donenfeld
2022-06-09 12:41 ` Marco Elver
2022-06-09 12:52 ` Petr Mladek [this message]
2022-06-09 12:31 ` [PATCH] " Geert Uytterhoeven
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YqHtIGI7ueuI/ovx@alley \
--to=pmladek@suse.com \
--cc=Jason@zx2c4.com \
--cc=dvyukov@google.com \
--cc=elver@google.com \
--cc=geert+renesas@glider.be \
--cc=geert@linux-m68k.org \
--cc=glider@google.com \
--cc=john.ogness@linutronix.de \
--cc=kasan-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox