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From:   "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     Ira Weiny <ira.weiny@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Will Deacon <will@kernel.org>,
        Peter Collingbourne <pcc@google.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-kernel@vger.kernel.org,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        outreachy@lists.linux.dev,
        "Acked-by : Mike Rapoport" <rppt@linux.ibm.com>
Subject: Re: [PATCH v2 1/4] mm/highmem: Fix kernel-doc warnings in highmem*.h
Date:   Wed, 27 Apr 2022 07:28:13 +0200
Message-ID: <2383038.jE0xQCEvom@leap>
In-Reply-To: <YmfRynAhuSWz9H+e@linutronix.de>
References: <20220425162400.11334-1-fmdefrancesco@gmail.com> <4396926.LvFx2qVVIh@leap> <YmfRynAhuSWz9H+e@linutronix.de>
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On marted=C3=AC 26 aprile 2022 13:04:42 CEST Sebastian Andrzej Siewior wrot=
e:
> On 2022-04-26 11:43:03 [+0200], Fabio M. De Francesco wrote:
>=20
> Either way, according to the code kmap_atomic() does not always disable
> preemption=20

Hi Sebastian,

In my last email (for patch 4/4) I wrote that I would add a deprecation=20
notice to kunmap_local() and would talk about thread locality in=20
kmap_local_page(). I want to confirm that I'll do these changes in v3.

Then I closed that email asking if I was still overlooking something.=20
Consider that I'm relatively new to kernel development and that it's just=20
something I do in my spare time. So I was pretty sure I was still missing=20
something :)

After reading again the code of kmap_atomic() (as you suggested - thanks!)=
=20
I noted that you correctly say that kmap_atomic() does not always disables=
=20
preemption (i.e., preemption is disabled only for !PREEMPT_RT kernel's =20
configurations).

Therefore I'll also change the first sentence of kunmap_local() to the=20
following:

"[It] Unmaps an address previously mapped by kmap_atomic() and re-enables=20
pagefaults and preemption (the latter disabled only for !PREEMP_RT=20
configurations).".

I will also be making this change in v3.

Can you please say if I'm still missing something?

Thanks,

=46abio