linux-kernel - Re: [PATCH v6 02/17] arm64: hibernate: pass the allocated pgdp to ttbr0

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Message-ID: <bb937db3-f23a-809b-4ad8-ca86f689554d@arm.com>
Date:   Fri, 11 Oct 2019 19:17:22 +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, marc.zyngier@....com,
        vladimir.murzin@....com, matthias.bgg@...il.com,
        bhsharma@...hat.com, linux-mm@...ck.org, mark.rutland@....com
Subject: Re: [PATCH v6 02/17] arm64: hibernate: pass the allocated pgdp to
 ttbr0

Hi Pavel,

On 04/10/2019 19:52, Pavel Tatashin wrote:
> ttbr0 should be set to the beginning of pgdp, however, currently
> in create_safe_exec_page it is set to pgdp after pgd_offset_raw(),
> which works by accident.
> 
> Fixes: 0194e760f7d2 ("arm64: hibernate: avoid potential TLB conflict")

(That was a 'break before make' fix, the affected code comes from:
 82869ac57b5d (""arm64: kernel: Add support for hibernate/suspend-to-disk))

But, it works in all one circumstances its used: we know all the top bits will be zero.
I agree its by accident and we should fix it.

I don't think we should send it to stable.
Please drop the fixes tag, with that:
Reviewed-by: James Morse <james.morse@....com>


Thanks,

James


[0] https://lore.kernel.org/linux-arm-kernel/ddd81093-89fc-5146-0b33-ad3bd9a1c10c@arm.com/