Re: [PATCH] arm64: fix add kasan bug

[Catalin Marinas]

On Thu, Dec 31, 2015 at 10:09:09AM +0000, zhongjiang wrote:
> From: zhong jiang <zhongjiang@xxxxxxxxxx>
> 
> In general, each process have 16kb stack space to use, but
> stack need extra space to store red_zone when kasan enable.
> the patch fix above question.
> 
> Signed-off-by: zhong jiang <zhongjiang@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/thread_info.h | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index 90c7ff2..45b5a7e 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
[...]
> +#ifdef CONFIG_KASAN
> +#define THREAD_SIZE		32768
> +#else
>  #define THREAD_SIZE		16384
> +#endif

I'm not really keen on increasing the stack size to 32KB when KASan is
enabled (that's 8 4K pages). Have you actually seen a real problem with
the default size? How large is the red_zone?

With 4.5 we are going for separate IRQ stack on arm64, so the typical
stack overflow case no longer exists.

-- 
Catalin
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