linux-kernel - Re: [PATCH v5 3/6] arch/x86: Implement text_alloc() and text

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Date:   Sat, 25 Jul 2020 05:03:32 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Marco Elver <elver@...gle.com>,
        Babu Moger <Babu.Moger@....com>,
        Brian Gerst <brgerst@...il.com>,
        Nayna Jain <nayna@...ux.ibm.com>
Subject: Re: [PATCH v5 3/6] arch/x86: Implement text_alloc() and text_free()

On Fri, Jul 24, 2020 at 11:22:58AM +0200, Ingo Molnar wrote:
> 
> * Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com> wrote:
> 
> > +void text_free(void *region)
> > +{
> > +	/*
> > +	 * This memory may be RO, and freeing RO memory in an interrupt is not
> > +	 * supported by vmalloc.
> > +	 */
> > +	lockdep_assert_irqs_enabled();
> > +
> > +	vfree(region);
> 
> Had to dig around a bit to find the source of this restriction. Might 
> make sense to clarify this comment to:
> 
> 	/*
> 	 * This memory may be read-only, and freeing VM_FLUSH_RESET_PERMS memory
> 	 * in an interrupt is not supported by vmalloc.
> 	 */

This definitely clarifies and is a better explanation. I updated the
commit accordingly. Thank you.

> 
> Thanks,
> 
> 	Ingo

/Jarkko