linux-kernel - Re: [PATCH v9 05/18] arm64: trans_pgd: pass NULL instead of init_mm to *

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Message-ID: <d19f4bc5-ad5b-5dad-0d50-271817b6c9aa@arm.com>
Date:   Wed, 29 Apr 2020 18:01:11 +0100
From:   James Morse <james.morse@....com>
To:     Pavel Tatashin <pasha.tatashin@...een.com>
Cc:     jmorris@...ei.org, sashal@...nel.org, ebiederm@...ssion.com,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        corbet@....net, catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, maz@...nel.org,
        vladimir.murzin@....com, matthias.bgg@...il.com,
        bhsharma@...hat.com, linux-mm@...ck.org, mark.rutland@....com,
        steve.capper@....com, rfontana@...hat.com, tglx@...utronix.de,
        selindag@...il.com
Subject: Re: [PATCH v9 05/18] arm64: trans_pgd: pass NULL instead of init_mm
 to *_populate functions

Hi Pavel,

On 26/03/2020 03:24, Pavel Tatashin wrote:
> trans_pgd_* should be independent from mm context because the tables that
> are created by this code are used when there are no mm context around, as
> it is between kernels. Simply replace mm_init's with NULL.

arm64's p?d_populate() helpers don't use the mm parameter, so it doesn't make any
difference. This was originally done so that if we ever needed anything from the mm, we
didn't get a NULL dereference or EL0 behaviour due to a future '!= &init_mm'.

If you think it matters,
Acked-by: James Morse <james.morse@....com>


Thanks,

James