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Date:   Thu, 10 Jan 2019 16:32:20 +0000
From:   Will Deacon <will.deacon@arm.com>
To:     Arnd Bergmann <arnd@arndb.de>
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Subject: Re: [PATCH 06/15] ARM: add migrate_pages() system call
Message-ID: <20190110163220.GB31683@fuggles.cambridge.arm.com>
References: <20190110162435.309262-1-arnd@arndb.de>
 <20190110162435.309262-7-arnd@arndb.de>
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On Thu, Jan 10, 2019 at 05:24:26PM +0100, Arnd Bergmann wrote:
> The migrate_pages system call has an assigned number on all architectures
> except ARM. When it got added initially in commit d80ade7b3231 ("ARM:
> Fix warning: #warning syscall migrate_pages not implemented"), it was
> intentionally left out based on the observation that there are no 32-bit
> ARM NUMA systems.
> 
> However, there are now arm64 NUMA machines that can in theory run 32-bit
> kernels (actually enabling NUMA there would require additional work)
> as well as 32-bit user space on 64-bit kernels, so that argument is no
> longer very strong.
> 
> Assigning the number lets us use the system call on 64-bit kernels as well
> as providing a more consistent set of syscalls across architectures.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/arm/include/asm/unistd.h     | 1 -
>  arch/arm/tools/syscall.tbl        | 1 +
>  arch/arm64/include/asm/unistd.h   | 2 +-
>  arch/arm64/include/asm/unistd32.h | 2 ++
>  4 files changed, 4 insertions(+), 2 deletions(-)

[...]

> diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
> index 04ee190b90fe..355fe2bc035b 100644
> --- a/arch/arm64/include/asm/unistd32.h
> +++ b/arch/arm64/include/asm/unistd32.h
> @@ -821,6 +821,8 @@ __SYSCALL(__NR_statx, sys_statx)
>  __SYSCALL(__NR_rseq, sys_rseq)
>  #define __NR_io_pgetevents 399
>  __SYSCALL(__NR_io_pgetevents, compat_sys_io_pgetevents)
> +#define __NR_migrate_pages 400
> +__SYSCALL(__NR_migrate_pages, sys_migrate_pages)

Should be compat_sys_migrate_pages instead?

Will