linux-kernel - Re: [patch 1/5] vmalloc: do not check for freed locks on user maps

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Date:	Thu, 6 Mar 2008 03:28:19 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg KH <greg@...ah.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [patch 1/5] vmalloc: do not check for freed locks on user maps

On Thursday 06 March 2008 03:03, Thomas Gleixner wrote: 
> User maps do not contain kernel internal objects. No need to check
> them.

Why not? Depends on your definition of kernel internal... and
objects ;)

Drivers could create and manage some objects in this vmalloc
area. They are no longer internal if you map them to userspace,
but I still don't think you want to vunmap it until those
object lifetimes are finished.


> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Acked-by: Ingo Molnar <mingo@...e.hu>
> ---
>  mm/vmalloc.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> Index: linux-2.6/mm/vmalloc.c
> ===================================================================
> --- linux-2.6.orig/mm/vmalloc.c
> +++ linux-2.6/mm/vmalloc.c
> @@ -382,7 +382,8 @@ static void __vunmap(const void *addr, i
>  		return;
>  	}
>
> -	debug_check_no_locks_freed(addr, area->size);
> +	if (!(area->flags & VM_USERMAP))
> +		debug_check_no_locks_freed(addr, area->size);
>
>  	if (deallocate_pages) {
>  		int i;

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