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From: Catalin Marinas <catalin.marinas@arm.com>
To: Breno Leitao <leitao@debian.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Waiman Long <llong@redhat.com>, Gu Bowen <gubowen5@huawei.com>,
	stable@vger.kernel.org, linux-mm@kvack.org,
	Lu Jialin <lujialin4@huawei.com>
Subject: Re: [PATCH] mm: Fix possible deadlock in console_trylock_spinning
Date: Mon, 4 Aug 2025 19:28:42 +0100	[thread overview]
Message-ID: <aJD72syGyJs203Mw@arm.com> (raw)
In-Reply-To: <o2gpvdtxqrdfrsbayorvzvjqcreb45puojpgfye7dimbuuvbdt@gxquukahrxo7>

On Mon, Aug 04, 2025 at 05:34:10AM -0700, Breno Leitao wrote:
> On Mon, Aug 04, 2025 at 01:08:15PM +0100, Catalin Marinas wrote:
> 
> > I'm surprised we haven't seen these until recently. Has printk always
> > allocated memory?
> 
> I can talk about netconsole, and the answer is yes!
> 
> weird enought, lockdep never picked this issue, and I have a few set of
> hosts running kmemleak and lockdep for a while.
> 
> This time was different because I have decided to invstiage the code,
> and found the deadlock. Still, no lockdep complain at all.

I guess it's because kmemleak is quiet in general, unless problems are
found, and lockdep never registered this combination - printk() called
with the kmemleak_lock held.

Thanks for investigating.

-- 
Catalin


  reply	other threads:[~2025-08-04 18:28 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-30  9:49 [PATCH] mm: Fix possible deadlock in console_trylock_spinning Gu Bowen
2025-08-01 22:33 ` Andrew Morton
2025-08-02  3:09   ` Waiman Long
2025-08-02  3:53     ` Andrew Morton
2025-08-04 12:08       ` Catalin Marinas
2025-08-04 12:34         ` Breno Leitao
2025-08-04 18:28           ` Catalin Marinas [this message]
2025-08-05  7:44             ` Gu Bowen
2025-08-06 15:34     ` John Ogness
2025-08-07  3:22       ` Gu Bowen
2025-08-01 23:52 ` Andrew Morton
2025-08-11 14:33   ` Petr Mladek

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