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From: Yeoreum Yun <yeoreum.yun@arm.com>
To: Byungchul Park <byungchul@sk.com>
Cc: ryabinin.a.a@gmail.com, glider@google.com, andreyknvl@gmail.com,
	dvyukov@google.com, vincenzo.frascino@arm.com,
	kpm@linux-foundation.org, bigeasy@linutronix.de,
	clrkwllms@kernel.org, rostedt@goodmis.org,
	max.byungchul.park@gmail.com, kasan-dev@googlegroups.com,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-rt-devel@lists.linux.dev, nd@arm.com,
	Yunseong Kim <ysk@kzalloc.com>,
	kernel_team@skhynix.com
Subject: Re: [PATCH] kasan: don't call find_vm_area() in in_interrupt() for possible deadlock
Date: Wed, 2 Jul 2025 07:28:21 +0100	[thread overview]
Message-ID: <aGTRhaHrkjCNb2S4@e129823.arm.com> (raw)
In-Reply-To: <20250702060949.GB5358@system.software.com>

Hi Byungchul,

> > >
> > > CPU0                                CPU1
> > > vmalloc();
> > >  alloc_vmap_area();
> > >   spin_lock(&vn->busy.lock)
> > 			^
> > 	Here, it should be spin_lock_bh(&vn->busy.lock).
>
> spin_lock_irqsave(&vn->busy.lock) might be even better, assuming
> find_vm_area() could be called with a critcal section of *_irq() or
> something.

Agree for this change and I also thought about it.
But, I'm not sure changing to spin_lock_irqsave() is *better*
since it makes a unexpected schedule delay whenever
vmalloc_info_show() is called via proc.

Also, I think the find_vm_area() is designed for task context not
for atomic context. so it seems the misusage in the kasan.

Am I missing something?

Thanks.

--
Sincerely,
Yeoreum Yun


  reply	other threads:[~2025-07-02  6:29 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-01 20:35 Yeoreum Yun
2025-07-02  6:01 ` Byungchul Park
2025-07-02  6:09   ` Byungchul Park
2025-07-02  6:28     ` Yeoreum Yun [this message]
2025-07-02 15:46 ` Andrey Ryabinin
2025-07-02 16:04   ` Yeoreum Yun
2025-07-03 17:10     ` Andrey Ryabinin
2025-07-03 18:07       ` Yeoreum Yun
2025-07-07  7:59 ` Sebastian Andrzej Siewior
2025-07-07  8:07   ` Yeoreum Yun

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