linux-kernel - Re: [PATCH 01/33] mm: introduce get_user_pages

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Message-ID: <20160215061441.GB31846@linux.vnet.ibm.com>
Date:	Mon, 15 Feb 2016 11:44:41 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Dave Hansen <dave@...1.net>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
	torvalds@...ux-foundation.org, dave.hansen@...ux.intel.com,
	vbabka@...e.cz, akpm@...ux-foundation.org,
	kirill.shutemov@...ux.intel.com, aarcange@...hat.com,
	n-horiguchi@...jp.nec.com, jack@...e.cz
Subject: Re: [PATCH 01/33] mm: introduce get_user_pages_remote()

> diff -puN kernel/events/uprobes.c~introduce-get_user_pages_remote kernel/events/uprobes.c
> --- a/kernel/events/uprobes.c~introduce-get_user_pages_remote	2016-02-12 10:44:13.178107026 -0800
> +++ b/kernel/events/uprobes.c	2016-02-12 10:44:13.193107711 -0800
> @@ -299,7 +299,7 @@ int uprobe_write_opcode(struct mm_struct
> 
>  retry:
>  	/* Read the page with vaddr into memory */
> -	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
> +	ret = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
>  	if (ret <= 0)
>  		return ret;
> 
> @@ -1700,7 +1700,13 @@ static int is_trap_at_addr(struct mm_str
>  	if (likely(result == 0))
>  		goto out;
> 
> -	result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
> +	/*
> +	 * The NULL 'tsk' here ensures that any faults that occur here
> +	 * will not be accounted to the task.  'mm' *is* current->mm,
> +	 * but we treat this as a 'remote' access since it is
> +	 * essentially a kernel access to the memory.
> +	 */
> +	result = get_user_pages_remote(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
>  	if (result < 0)
>  		return result;
> 

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

-- 
Thanks and Regards
Srikar Dronamraju