linux-kernel - Re: [PATCH 4.9 39/92] efi/arm: Revert deferred unmap of early memmap mapping

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Date:   Thu, 29 Nov 2018 16:03:49 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        stable <stable@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-efi <linux-efi@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>, sashal@...nel.org
Subject: Re: [PATCH 4.9 39/92] efi/arm: Revert deferred unmap of early memmap mapping

On Thu, 29 Nov 2018 at 16:02, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
>
> On Thu, Nov 29, 2018 at 03:28:44PM +0100, Ard Biesheuvel wrote:
> > On Thu, 29 Nov 2018 at 15:21, Greg Kroah-Hartman
> > <gregkh@...uxfoundation.org> wrote:
> > >
> > > 4.9-stable review patch.  If anyone has any objections, please let me know.
> > >
> > > ------------------
> > >
> > > [ Upstream commit 33412b8673135b18ea42beb7f5117ed0091798b6 ]
> > >
> > > Commit:
> > >
> > >   3ea86495aef2 ("efi/arm: preserve early mapping of UEFI memory map longer for BGRT")
> > >
> > > deferred the unmap of the early mapping of the UEFI memory map to
> > > accommodate the ACPI BGRT code, which looks up the memory type that
> > > backs the BGRT table to validate it against the requirements of the UEFI spec.
> > >
> > > Unfortunately, this causes problems on ARM, which does not permit
> > > early mappings to persist after paging_init() is called, resulting
> > > in a WARN() splat. Since we don't support the BGRT table on ARM anway,
> > > let's revert ARM to the old behaviour, which is to take down the
> > > early mapping at the end of efi_init().
> > >
> > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> > > Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> > > Cc: Peter Zijlstra <peterz@...radead.org>
> > > Cc: Thomas Gleixner <tglx@...utronix.de>
> > > Cc: linux-efi@...r.kernel.org
> > > Fixes: 3ea86495aef2 ("efi/arm: preserve early mapping of UEFI memory ...")
> >
> > This commit is only in v4.19 as far as I know. Does it even apply?
>
> This commit is in the following releases:
>         4.9.129 4.14.72 4.18.10 4.19
>
> so it should apply :)
>

Ah, of course.

I didn't realize (or failed to remember) that it had been taken into -stable.

Thanks,