linux-kernel - Re: [PATCH] md: Replace deprecated kmap_atomic() with kmap_local

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Message-ID: <CAPhsuW6y=KrncO1HMQwC-fL5qLi-BiLBuHix-Zq_yh-h06FV6A@mail.gmail.com>
Date: Wed, 8 Jan 2025 13:43:20 -0800
From: Song Liu <song@...nel.org>
To: me@...idreaver.com
Cc: Yu Kuai <yukuai3@...wei.com>, linux-raid@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Krister Johansen <kjlx@...pleofstupid.com>, 
	Ira Weiny <ira.weiny@...el.com>, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] md: Replace deprecated kmap_atomic() with kmap_local_page()

On Wed, Jan 8, 2025 at 11:23 AM David Reaver <me@...idreaver.com> wrote:
>
> kmap_atomic() is deprecated and should be replaced with kmap_local_page()
> [1][2]. kmap_local_page() is faster in kernels with HIGHMEM enabled, can
> take page faults, and allows preemption.
>
> According to [2], this is safe as long as the code between kmap_atomic()
> and kunmap_atomic() does not implicitly depend on disabling page faults or
> preemption. It appears to me that none of the call sites in this patch
> depend on disabling page faults or preemption; they are all mapping a page
> to simply extract some information from it or print some debug info.
>
> [1] https://lwn.net/Articles/836144/
> [2] https://docs.kernel.org/mm/highmem.html#temporary-virtual-mappings
>
> Signed-off-by: David Reaver <me@...idreaver.com>

LGTM. Applied to md-6.14.

Thanks for the patch!

Song