linux-kernel - Re: [PATCH] x86/mm: Pre-allocate p4d/pud pages for vmalloc area

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Date:   Fri, 26 Jun 2020 13:07:31 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Joerg Roedel <joro@...tes.org>
Cc:     x86@...nel.org, hpa@...or.com,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH] x86/mm: Pre-allocate p4d/pud pages for vmalloc area

On Fri, Jun 26, 2020 at 11:34:50AM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> Pre-allocate the page-table pages for the vmalloc area at the level
> which needs synchronization on x86. This is P4D for 5-level and PUD
> for 4-level paging.
> 
> Doing this at boot makes sure all page-tables in the system have these
> pages already and do not need to be synchronized at runtime. The
> runtime synchronizatin takes the pgd_lock and iterates over all
> page-tables in the system, so it can take quite long and is better
> avoided.
> 
> Signed-off-by: Joerg Roedel <jroedel@...e.de>
> ---

Can't we now remove arch_sync_kernel_mappings() from this same file?