linux-kernel - Re: [PATCH 7/8] mm: allow preemption in apply_to_pte

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Message-Id: <20090407143833.a6841a8b.akpm@linux-foundation.org>
Date:	Tue, 7 Apr 2009 14:38:33 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	x86@...nel.org, mingo@...e.hu, linux-kernel@...r.kernel.org,
	a.p.zijlstra@...llo.nl, nickpiggin@...oo.com.au,
	tglx@...utronix.de, jeremy.fitzhardinge@...rix.com
Subject: Re: [PATCH 7/8] mm: allow preemption in apply_to_pte_range

On Fri, 27 Mar 2009 11:02:42 -0700
Jeremy Fitzhardinge <jeremy@...p.org> wrote:

> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
> 
> Impact: allow preemption in apply_to_pte_range updates to init_mm
> 
> Preemption is now allowed for lazy mmu mode, so don't disable
> it for the inner loop of apply_to_pte_range.  This only applies
> when doing updates to init_mm; user pagetables are still modified
> under the pte lock, so preemption is disabled anyway.
> 
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
> ---
>  mm/memory.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memory.c b/mm/memory.c
> index 27f8677..ef11ac6 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1722,7 +1722,6 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
>  
>  	BUG_ON(pmd_huge(*pmd));
>  
> -	preempt_disable();
>  	arch_enter_lazy_mmu_mode();
>  
>  	token = pmd_pgtable(*pmd);
> @@ -1734,7 +1733,6 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
>  	} while (pte++, addr += PAGE_SIZE, addr != end);
>  
>  	arch_leave_lazy_mmu_mode();
> -	preempt_enable();
>  
>  	if (mm != &init_mm)
>  		pte_unmap_unlock(pte-1, ptl);

So across the aptch series the aggregate change to mm/ is nil, and this
is wholly an x86 patch series?

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