linux-kernel - Re: [PATCH 01/11] x86/mm: make MMU_GATHER_RCU_TABLE

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Message-ID: <b7078006-83d0-4820-916e-f717b6005a3e@bytedance.com>
Date: Mon, 23 Dec 2024 14:01:25 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: Rik van Riel <riel@...riel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, kernel-team@...a.com,
 dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
 tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
 akpm@...ux-foundation.org, linux-mm@...ck.org
Subject: Re: [PATCH 01/11] x86/mm: make MMU_GATHER_RCU_TABLE_FREE
 unconditional

Very happy to see this change!

On 2024/12/23 10:55, Rik van Riel wrote:
> Currently x86 usse CONFIG_MMU_GATHER_TABLE_FREE when using
                 ^
                 use

> paravirt, and not when running on bare metal.
> 
> There is no real good reason to do things differently for
> each setup. Make them all the same.
> 
> Signed-off-by: Rik van Riel <riel@...riel.com>
> Suggested-by: Peter Zijlstra <peterz@...radead.org>
> ---
>   arch/x86/Kconfig           | 2 +-
>   arch/x86/kernel/paravirt.c | 7 +------
>   2 files changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 9d7bd0ae48c4..e8743f8c9fd0 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -274,7 +274,7 @@ config X86
>   	select HAVE_PCI
>   	select HAVE_PERF_REGS
>   	select HAVE_PERF_USER_STACK_DUMP
> -	select MMU_GATHER_RCU_TABLE_FREE	if PARAVIRT
> +	select MMU_GATHER_RCU_TABLE_FREE
>   	select MMU_GATHER_MERGE_VMAS
>   	select HAVE_POSIX_CPU_TIMERS_TASK_WORK
>   	select HAVE_REGS_AND_STACK_ACCESS_API
> diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
> index fec381533555..2b78a6b466ed 100644
> --- a/arch/x86/kernel/paravirt.c
> +++ b/arch/x86/kernel/paravirt.c
> @@ -59,11 +59,6 @@ void __init native_pv_lock_init(void)
>   		static_branch_enable(&virt_spin_lock_key);
>   }
>   
> -static void native_tlb_remove_table(struct mmu_gather *tlb, void *table)
> -{
> -	tlb_remove_page(tlb, table);
> -}
> -
>   struct static_key paravirt_steal_enabled;
>   struct static_key paravirt_steal_rq_enabled;
>   
> @@ -191,7 +186,7 @@ struct paravirt_patch_template pv_ops = {
>   	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
>   	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
>   	.mmu.flush_tlb_multi	= native_flush_tlb_multi,
> -	.mmu.tlb_remove_table	= native_tlb_remove_table,
> +	.mmu.tlb_remove_table	= tlb_remove_table,
>   
>   	.mmu.exit_mmap		= paravirt_nop,
>   	.mmu.notify_page_enc_status_changed	= paravirt_nop,

It look like this patch series is not based on the latest linux-next.

In addition to the above case, maybe the paravirt_tlb_remove_table()
in arch/x86/mm/pgtable.c also needs to be changed to tlb_remove_table()?

Thanks,
Qi