linux-kernel - Re: [PATCH] virtio: console: Replace deprecated kmap_atomic with kmap_local

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <71ebf77ed3f006e950a692368c87726c74e9063d.camel@kernel.org>
Date: Thu, 09 Jan 2025 11:00:33 +0100
From: Amit Shah <amit@...nel.org>
To: David Reaver <me@...idreaver.com>, Arnd Bergmann <arnd@...db.de>, Greg
 Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: virtualization@...ts.linux.dev, linux-kernel@...r.kernel.org, Ira Weiny
	 <ira.weiny@...el.com>, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] virtio: console: Replace deprecated kmap_atomic with
 kmap_local_page

On Wed, 2025-01-08 at 19:59 -0800, David Reaver 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 replacement is safe as long as the code
> between
> kmap_atomic() and kunmap_atomic() does not implicitly depend on
> disabling
> page faults or preemption. In this patch, the only thing happening
> between
> mapping and unmapping the page is a memcpy, and I don't suspect it
> depends
> on disabling page faults or preemption.
> 
> [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>

Reviewed-by: Amit Shah <amit@...nel.org>