linux-kernel - Re: [PATCH v3] kasan: Don't call find_vm

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Message-ID: <CA+fCnZekjO6ajX5YDE2VgL3pzyawdVNkJ0g6-w0Xq15zdDdLog@mail.gmail.com>
Date: Mon, 17 Feb 2025 17:29:45 +0100
From: Andrey Konovalov <andreyknvl@...il.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: Waiman Long <longman@...hat.com>, Andrey Ryabinin <ryabinin.a.a@...il.com>, 
	Alexander Potapenko <glider@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Vincenzo Frascino <vincenzo.frascino@....com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Clark Williams <clrkwllms@...nel.org>, Steven Rostedt <rostedt@...dmis.org>, kasan-dev@...glegroups.com, 
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	linux-rt-devel@...ts.linux.dev, Nico Pache <npache@...hat.com>
Subject: Re: [PATCH v3] kasan: Don't call find_vm_area() in RT kernel

On Mon, Feb 17, 2025 at 4:43 PM Sebastian Andrzej Siewior
<bigeasy@...utronix.de> wrote:
>
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -370,6 +370,34 @@ static inline bool init_task_stack_addr(const void *addr)
> >                       sizeof(init_thread_union.stack));
> >  }
> >
> > +/*
> > + * RT kernel cannot call find_vm_area() in atomic context. For !RT kernel,
> > + * prevent spinlock_t inside raw_spinlock_t warning by raising wait-type
> > + * to WAIT_SLEEP.
> > + */
>
> Do we need this comment? I lacks context of why it is atomic. And we
> have it in the commit description.

I would prefer to have this in the comment, but with a full
explanation of why this needs to be done.