linux-kernel - Re: [PATCH v4 2/3] ioremap: Update pgtable free interfaces with addr

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Date:   Wed, 27 Jun 2018 16:56:33 +0100
From:   Will Deacon <will.deacon@....com>
To:     Toshi Kani <toshi.kani@....com>
Cc:     mhocko@...e.com, akpm@...ux-foundation.org, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, cpandya@...eaurora.org,
        linux-mm@...ck.org, x86@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>, stable@...r.kernel.org
Subject: Re: [PATCH v4 2/3] ioremap: Update pgtable free interfaces with addr

Hi Toshi,

On Wed, Jun 27, 2018 at 08:13:47AM -0600, Toshi Kani wrote:
> From: Chintan Pandya <cpandya@...eaurora.org>
> 
> The following kernel panic was observed on ARM64 platform due to a stale
> TLB entry.
> 
>  1. ioremap with 4K size, a valid pte page table is set.
>  2. iounmap it, its pte entry is set to 0.
>  3. ioremap the same address with 2M size, update its pmd entry with
>     a new value.
>  4. CPU may hit an exception because the old pmd entry is still in TLB,
>     which leads to a kernel panic.
> 
> Commit b6bdb7517c3d ("mm/vmalloc: add interfaces to free unmapped page
> table") has addressed this panic by falling to pte mappings in the above
> case on ARM64.
> 
> To support pmd mappings in all cases, TLB purge needs to be performed
> in this case on ARM64.
> 
> Add a new arg, 'addr', to pud_free_pmd_page() and pmd_free_pte_page()
> so that TLB purge can be added later in seprate patches.

So I acked v13 of Chintan's series posted here:

http://lists.infradead.org/pipermail/linux-arm-kernel/2018-June/582953.html

any chance this lot could all be merged together, please?

Will