linux-kernel - kmap() transformation: Question about copy_user

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Message-ID: <ZSBV+h/gjPWV7+Gj@runicha.com>
Date:   Sat, 7 Oct 2023 00:16:18 +0530
From:   Deepak R Varma <drv@...lo.com>
To:     Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Cc:     Ira Weiny <ira.weiny@...el.com>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Subject: kmap() transformation: Question about copy_user_highpage

Hello,
I am attempting to work on replacing the kmap[_atomic]() calls by
kmap_local_page() function call. A detail on this change can be found here [0].

I would like to know if this function: 
	arch/loongarch/mm/init.c::copy_user_highpage()
is currently in use or is it a dead code?

If this code is not in use, can this be removed instead? However, if it is in
use, can you comment why kmap_atomic() was preferred over kmap()
function call?

[0] https://lore.kernel.org/all/20201029222652.302358281@linutronix.de/

Thank you,
Deepak.