Re: [PATCH v2 0/2] riscv: Enable percpu page first chunk allocator

[Dennis Zhou]

Hello,

On Tue, Dec 12, 2023 at 10:34:55PM +0100, Alexandre Ghiti wrote:
> While working with pcpu variables, I noticed that riscv did not support
> first chunk allocation in the vmalloc area which may be needed as a fallback
> in case of a sparse NUMA configuration.
> 
> patch 1 starts by introducing a new function flush_cache_vmap_early() which
> is needed since a new vmalloc mapping is established and directly accessed:
> on riscv, this would likely fail in case of a reordered access or if the
> uarch caches invalid entries in TLB.
> Note that most architectures do not include asm-generic/cacheflush.h so to
> avoid build failures, this patch implements the new function on each of
> those architectures. For all architectures except riscv, this new function
> is implemented as a no-op to keep the existing behaviour but it likely
> needs another implementation.
> 
> patch 2 simply enables the page percpu first chunk allocator in riscv.
> 
> Changes in v2:
> - Rebase on top of 6.7
> - Define flush_cache_vmap_early() for all architectures that do
>   not include <asm-generic/cacheflush.h> to avoid build failures
> 
> Alexandre Ghiti (2):
>   mm: Introduce flush_cache_vmap_early()
>   riscv: Enable pcpu page first chunk allocator
> 
>  arch/arc/include/asm/cacheflush.h      | 1 +
>  arch/arm/include/asm/cacheflush.h      | 2 ++
>  arch/csky/abiv1/inc/abi/cacheflush.h   | 1 +
>  arch/csky/abiv2/inc/abi/cacheflush.h   | 1 +
>  arch/m68k/include/asm/cacheflush_mm.h  | 1 +
>  arch/mips/include/asm/cacheflush.h     | 2 ++
>  arch/nios2/include/asm/cacheflush.h    | 1 +
>  arch/parisc/include/asm/cacheflush.h   | 1 +
>  arch/riscv/Kconfig                     | 2 ++
>  arch/riscv/include/asm/cacheflush.h    | 3 ++-
>  arch/riscv/include/asm/tlbflush.h      | 1 +
>  arch/riscv/mm/kasan_init.c             | 8 ++++++++
>  arch/riscv/mm/tlbflush.c               | 5 +++++
>  arch/sh/include/asm/cacheflush.h       | 1 +
>  arch/sparc/include/asm/cacheflush_32.h | 1 +
>  arch/sparc/include/asm/cacheflush_64.h | 1 +
>  arch/xtensa/include/asm/cacheflush.h   | 6 ++++--
>  include/asm-generic/cacheflush.h       | 6 ++++++
>  mm/percpu.c                            | 8 +-------
>  19 files changed, 42 insertions(+), 10 deletions(-)
> 
> -- 
> 2.39.2
> 

Thanks for the quick v2. Applied to percpu#for-6.8.

Thanks,
Dennis