linux-kernel - Re: [PATCH 4/4] x86/mm: Only use tlb_remove

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Message-ID: <20180822221250.GB16015@u40b0340c692b58f6553c.ant.amazon.com>
Date:   Wed, 22 Aug 2018 15:12:50 -0700
From:   Eduardo Valentin <eduval@...zon.com>
To:     Peter Zijlstra <peterz@...radead.org>
CC:     <torvalds@...ux-foundation.org>, <luto@...nel.org>,
        <x86@...nel.org>, <bp@...en8.de>, <will.deacon@....com>,
        <riel@...riel.com>, <jannh@...gle.com>, <ascannell@...gle.com>,
        <dave.hansen@...el.com>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>
Subject: Re: [PATCH 4/4] x86/mm: Only use tlb_remove_table() for paravirt

Hey Peter,

On Wed, Aug 22, 2018 at 05:30:16PM +0200, Peter Zijlstra wrote:
> If we don't use paravirt; don't play unnecessary and complicated games
> to free page-tables.
> 
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  arch/x86/Kconfig                      |    2 +-
>  arch/x86/hyperv/mmu.c                 |    2 ++
>  arch/x86/include/asm/paravirt.h       |    5 +++++
>  arch/x86/include/asm/paravirt_types.h |    3 +++
>  arch/x86/include/asm/tlbflush.h       |    3 +++
>  arch/x86/kernel/kvm.c                 |    5 ++++-
>  arch/x86/kernel/paravirt.c            |    2 ++
>  arch/x86/mm/pgtable.c                 |    8 ++++----
>  arch/x86/xen/mmu_pv.c                 |    1 +
>  9 files changed, 25 insertions(+), 6 deletions(-)
> 

<cut>

> --- a/arch/x86/xen/mmu_pv.c
> +++ b/arch/x86/xen/mmu_pv.c
> @@ -2397,6 +2397,7 @@ static const struct pv_mmu_ops xen_mmu_o
>  	.flush_tlb_kernel = xen_flush_tlb,
>  	.flush_tlb_one_user = xen_flush_tlb_one_user,
>  	.flush_tlb_others = xen_flush_tlb_others,
> +	.tlb_remove_table = tlb_remove_table,

I tried compiling the series, and I am getting the following compilation error:

  CC      arch/x86/xen/mmu_pv.o
arch/x86/xen/mmu_pv.c:2400:22: error: ‘tlb_remove_table’ undeclared here (not in a function); did you mean ‘bus_remove_file’?
  .tlb_remove_table = tlb_remove_table,
                      ^~~~~~~~~~~~~~~~
                      bus_remove_file
make[4]: *** [arch/x86/xen/mmu_pv.o] Error 1


which I solved by:
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index a21988ec30d3..3114b7c76970 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -67,6 +67,7 @@
 #include <asm/init.h>
 #include <asm/pat.h>
 #include <asm/smp.h>
+#include <asm/tlb.h>
 
 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>


>  
>  	.pgd_alloc = xen_pgd_alloc,
>  	.pgd_free = xen_pgd_free,
> 
> 
> 

-- 
All the best,
Eduardo Valentin