linux-kernel - Re: [PATCH v17 15/15] arm64: trans_pgd: remove trans_pgd_map

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Date:   Thu, 30 Sep 2021 00:12:28 -0400
From:   Pasha Tatashin <pasha.tatashin@...een.com>
To:     Catalin Marinas <catalin.marinas@....com>
Cc:     James Morris <jmorris@...ei.org>, Sasha Levin <sashal@...nel.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        kexec mailing list <kexec@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jonathan Corbet <corbet@....net>,
        Will Deacon <will@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Vladimir Murzin <vladimir.murzin@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-mm <linux-mm@...ck.org>,
        Mark Rutland <mark.rutland@....com>, steve.capper@....com,
        rfontana@...hat.com, Thomas Gleixner <tglx@...utronix.de>,
        Selin Dag <selindag@...il.com>,
        Tyler Hicks <tyhicks@...ux.microsoft.com>,
        Pingfan Liu <kernelfans@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        madvenka@...ux.microsoft.com
Subject: Re: [PATCH v17 15/15] arm64: trans_pgd: remove trans_pgd_map_page()

On Wed, Sep 29, 2021 at 12:43 PM Catalin Marinas
<catalin.marinas@....com> wrote:
>
> On Thu, Sep 16, 2021 at 07:13:25PM -0400, Pasha Tatashin wrote:
> > The intend of trans_pgd_map_page() was to map contiguous range of VA
> > memory to the memory that is getting relocated during kexec. However,
> > since we are now using linear map instead of contiguous range this
> > function is not needed
> >
> > Suggested-by: Pingfan Liu <kernelfans@...il.com>
> > Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
> > ---
> >  arch/arm64/include/asm/trans_pgd.h |  5 +--
> >  arch/arm64/mm/trans_pgd.c          | 57 ------------------------------
> >  2 files changed, 1 insertion(+), 61 deletions(-)
> >
> > diff --git a/arch/arm64/include/asm/trans_pgd.h b/arch/arm64/include/asm/trans_pgd.h
> > index 7b04d32b102c..033d400a4ea4 100644
> > --- a/arch/arm64/include/asm/trans_pgd.h
> > +++ b/arch/arm64/include/asm/trans_pgd.h
> > @@ -15,7 +15,7 @@
> >  /*
> >   * trans_alloc_page
> >   *   - Allocator that should return exactly one zeroed page, if this
> > - *     allocator fails, trans_pgd_create_copy() and trans_pgd_map_page()
> > + *     allocator fails, trans_pgd_create_copy() and trans_pgd_idmap_page()
> >   *     return -ENOMEM error.
> >   *
> >   * trans_alloc_arg
> > @@ -30,9 +30,6 @@ struct trans_pgd_info {
> >  int trans_pgd_create_copy(struct trans_pgd_info *info, pgd_t **trans_pgd,
> >                         unsigned long start, unsigned long end);
> >
> > -int trans_pgd_map_page(struct trans_pgd_info *info, pgd_t *trans_pgd,
> > -                    void *page, unsigned long dst_addr, pgprot_t pgprot);
>
> So this function never got used in mainline after commit 7018d467ff2d
> ("arm64: trans_pgd: hibernate: idmap the single page that holds the copy
> page routines"). I guess it's because we merged part of v10 of this
> series and in v12 you dropped the contiguous VA range in favour of a
> copy of the linear map.

This is exactly right. This function was meant for the contiguous-va
relocation version of this series.

Pasha