Re: [PATCH 02/10] mm: workingset: tell cache transitions from workingset thrashing

[Johannes Weiner]

On Mon, Jul 23, 2018 at 05:35:35PM +0200, Arnd Bergmann wrote:
> On Mon, Jul 23, 2018 at 5:23 PM, Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
> > From 1d24635a6c7cd395bad5c29a3b9e5d2e98d9ab84 Mon Sep 17 00:00:00 2001
> > From: Johannes Weiner <hannes@xxxxxxxxxxx>
> > Date: Mon, 23 Jul 2018 10:18:23 -0400
> > Subject: [PATCH] arm64: fix vmemmap BUILD_BUG_ON() triggering on !vmemmap
> >  setups
> >
> > Arnd reports the following arm64 randconfig build error with the PSI
> > patches that add another page flag:
> >
> 
> You could add further text here that I had just added to my
> patch description (not sent):
> 
>     Further experiments show that the build error already existed before,
>     but was only triggered with larger values of CONFIG_NR_CPU and/or
>     CONFIG_NODES_SHIFT that might be used in actual configurations but
>     not in randconfig builds.
> 
>     With longer CPU and node masks, I could recreate the problem with
>     kernels as old as linux-4.7 when arm64 NUMA support got added.
> 
>     Cc: stable@xxxxxxxxxxxxxxx
>     Fixes: 1a2db300348b ("arm64, numa: Add NUMA support for arm64 platforms.")
>     Fixes: 3e1907d5bf5a ("arm64: mm: move vmemmap region right below
> the linear region")

Sure thing.

> >  arch/arm64/mm/init.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 1b18b4722420..72c9b6778b0a 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -611,11 +611,13 @@ void __init mem_init(void)
> >         BUILD_BUG_ON(TASK_SIZE_32                       > TASK_SIZE_64);
> >  #endif
> >
> > +#ifndef CONFIG_SPARSEMEM_VMEMMAP
> >         /*
> 
> I tested it on two broken configurations, and found that you have
> a typo here, it should be 'ifdef', not 'ifndef'. With that change, it
> seems to build fine.
> 
> Tested-by: Arnd Bergmann <arnd@xxxxxxxx>

Thanks for testing it, I don't have a cross-compile toolchain set up.

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