linux-kernel - Re: [PATCH 05/12] mm: Introduce arch_pgd_init

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Message-ID: <20150612211220.GC18966@redhat.com>
Date:	Fri, 12 Jun 2015 23:12:20 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org, linux-mml@...r.kernel.org,
	Andy Lutomirski <luto@...capital.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Waiman Long <Waiman.Long@...com>
Subject: Re: [PATCH 05/12] mm: Introduce arch_pgd_init_late()

On 06/11, Ingo Molnar wrote:
>
> @@ -1592,6 +1592,22 @@ static struct task_struct *copy_process(unsigned long clone_flags,
>  	syscall_tracepoint_update(p);
>  	write_unlock_irq(&tasklist_lock);
>  
> +	/*
> +	 * If we have a new PGD then initialize it:
> +	 *
> +	 * This method is called after a task has been made visible
> +	 * on the task list already.
> +	 *
> +	 * Architectures that manage per task kernel pagetables
> +	 * might use this callback to initialize them after they
> +	 * are already visible to new updates.
> +	 *
> +	 * NOTE: any user-space parts of the PGD are already initialized
> +	 *       and must not be clobbered.
> +	 */
> +	if (p->mm != current->mm)
> +		arch_pgd_init_late(p->mm, p->mm->pgd);
> +

Cosmetic, but imo

	if (!(clone_flags & CLONE_VM))
		arch_pgd_init_late(...);

will look better and more consistent.

Oleg.

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