linux-kernel - Re: [PATCH] kasan: make report

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Message-ID: <Z0DHZIEI5hobBUwn@jkangas-thinkpadp1gen3.rmtuswa.csb>
Date: Fri, 22 Nov 2024 10:03:16 -0800
From: Jared Kangas <jkangas@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: ryabinin.a.a@...il.com, glider@...gle.com, andreyknvl@...il.com,
	dvyukov@...gle.com, vincenzo.frascino@....com,
	kasan-dev@...glegroups.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kasan: make report_lock a raw spinlock

On Thu, Nov 21, 2024 at 10:28:09PM -0800, Andrew Morton wrote:
> On Tue, 19 Nov 2024 13:02:34 -0800 Jared Kangas <jkangas@...hat.com> wrote:
> 
> > If PREEMPT_RT is enabled, report_lock is a sleeping spinlock and must
> > not be locked when IRQs are disabled. However, KASAN reports may be
> > triggered in such contexts. For example:
> > 
> >         char *s = kzalloc(1, GFP_KERNEL);
> >         kfree(s);
> >         local_irq_disable();
> >         char c = *s;  /* KASAN report here leads to spin_lock() */
> >         local_irq_enable();
> > 
> > Make report_spinlock a raw spinlock to prevent rescheduling when
> > PREEMPT_RT is enabled.
> 
> So I assume we want this backported into 6.12.x?

Sorry for missing that; I think a backport of the patch would be
appropriate.

> If so, please help us identify a suitable Fixes: commit.

Fixes: 342a93247e08 ("locking/spinlock: Provide RT variant header: <linux/spinlock_rt.h>")