linux-kernel - Re: [PATCH 1/2] kmemleak: Inform kmemleak about kernel stack allocation

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Message-ID: <20090829132954.GB24123@elte.hu>
Date:	Sat, 29 Aug 2009 15:29:54 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH 1/2] kmemleak: Inform kmemleak about kernel stack
	allocation


* Catalin Marinas <catalin.marinas@....com> wrote:

> Traversing all the tasks in the system for scanning the kernel 
> stacks requires locking which increases the kernel latency 
> considerably. This patch informs kmemleak about newly allocated or 
> freed stacks so that they are treated as any other allocated 
> object. Subsequent patch will remove the explicit stack scanning 
> from mm/kmemleak.c.
> 
> Signed-off-by: Catalin Marinas <catalin.marinas@....com>
> Cc: Ingo Molnar <mingo@...hat.com>
> ---
>  arch/x86/include/asm/thread_info.h |    7 ++++++-
>  arch/x86/kernel/process.c          |    2 ++
>  kernel/fork.c                      |    7 ++++++-
>  3 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
> index fad7d40..f26432a 100644
> --- a/arch/x86/include/asm/thread_info.h
> +++ b/arch/x86/include/asm/thread_info.h
> @@ -162,7 +162,12 @@ struct thread_info {
>  #define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
>  
>  #define alloc_thread_info(tsk)						\
> -	((struct thread_info *)__get_free_pages(THREAD_FLAGS, THREAD_ORDER))
> +({									\
> +	struct thread_info *ti = (struct thread_info *)			\
> +		__get_free_pages(THREAD_FLAGS, THREAD_ORDER);		\
> +	kmemleak_alloc(ti, THREAD_SIZE, 1, THREAD_FLAGS);		\
> +	ti;								\
> +})

Sidenote:this used to be a trivial wrapper to gfp so it was 
borderline OK as a CPP macro - now it's a non-trivial CPP wrapper 
macro which is not OK. Mind converting it to an inline function?

	Ingo
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