linux-kernel - Re: [PATCH 1/7] uprobes: Move alloc_page() from xol_add_vma() to xol_alloc

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Message-ID: <20130108114607.GD1325@linux.vnet.ibm.com>
Date:	Tue, 8 Jan 2013 17:16:07 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Frank Eigler <fche@...hat.com>,
	Josh Stone <jistone@...hat.com>,
	"Suzuki K. Poulose" <suzuki@...ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] uprobes: Move alloc_page() from xol_add_vma() to
 xol_alloc_area()

* Oleg Nesterov <oleg@...hat.com> [2012-12-31 18:52:12]:

> Move alloc_page() from xol_add_vma() to xol_alloc_area() to cleanup
> the code. This separates the memory allocations and consolidates the
> -EALREADY cleanups and the error handling.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

(One simple check below)

Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>


> ---
>  kernel/events/uprobes.c |   32 +++++++++++++-------------------
>  1 files changed, 13 insertions(+), 19 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index f883813..1456f7d 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1041,22 +1041,14 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
>  /* Slot allocation for XOL */
>  static int xol_add_vma(struct xol_area *area)
>  {
> -	struct mm_struct *mm;
> -	int ret;
> -
> -	area->page = alloc_page(GFP_HIGHUSER);
> -	if (!area->page)
> -		return -ENOMEM;
> -
> -	ret = -EALREADY;
> -	mm = current->mm;
> +	struct mm_struct *mm = current->mm;
> +	int ret = -EALREADY;
> 
>  	down_write(&mm->mmap_sem);
>  	if (mm->uprobes_state.xol_area)
>  		goto fail;
> 
>  	ret = -ENOMEM;
> -
>  	/* Try to map as high as possible, this is only a hint. */
>  	area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0);
>  	if (area->vaddr & ~PAGE_MASK) {
> @@ -1072,11 +1064,8 @@ static int xol_add_vma(struct xol_area *area)
>  	smp_wmb();	/* pairs with get_xol_area() */
>  	mm->uprobes_state.xol_area = area;
>  	ret = 0;
> -
> -fail:
> + fail:

Not sure if the space before label is intentional?
Its true of other labels below also.

>  	up_write(&mm->mmap_sem);
> -	if (ret)
> -		__free_page(area->page);
> 
>  	return ret;
>  }
> @@ -1104,21 +1093,26 @@ static struct xol_area *xol_alloc_area(void)
> 
>  	area = kzalloc(sizeof(*area), GFP_KERNEL);
>  	if (unlikely(!area))
> -		return NULL;
> +		goto out;
> 
>  	area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL);
> -
>  	if (!area->bitmap)
> -		goto fail;
> +		goto free_area;
> +
> +	area->page = area->page = alloc_page(GFP_HIGHUSER);
> +	if (!area->page)
> +		goto free_bitmap;
> 
>  	init_waitqueue_head(&area->wq);
>  	if (!xol_add_vma(area))
>  		return area;
> 
> -fail:
> +	__free_page(area->page);
> + free_bitmap:
>  	kfree(area->bitmap);
> + free_area:
>  	kfree(area);
> -
> + out:
>  	return get_xol_area(current->mm);
>  }
> 
> -- 
> 1.5.5.1
> 

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