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Date:   Thu, 19 Nov 2020 08:46:01 +0000
From:   Mel Gorman <mgorman@suse.de>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
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        Andrew Morton <akpm@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>,
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        Ingo Molnar <mingo@kernel.org>,
        Juri Lelli <juri.lelli@redhat.com>,
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        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: Re: [patch V4 2/8] mm/highmem: Provide
 CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP
Message-ID: <20201119084601.GG3306@suse.de>
References: <20201118194838.753436396@linutronix.de>
 <20201118204007.028261233@linutronix.de>
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On Wed, Nov 18, 2020 at 01:13:57PM -0800, Linus Torvalds wrote:
> On Wed, Nov 18, 2020 at 12:58 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > Provide CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP which forces the temporary
> > mapping even for lowmem pages. This needs to be a seperate config switch
> > because this only works on architectures which do not have cache aliasing
> > problems.
> 
> Very good. And you made sure to have a comment to not enable it for
> production systems.
> 
> Hopefully people will even read it ;)
> 

And not start thinking it as a security hardening option.

-- 
Mel Gorman
SUSE Labs