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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH] proc: fix kflags to uflags copying in /proc/kpageflags
Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>, stable@kernel.org,
       LKML <linux-kernel@vger.kernel.org>, Matt Mackall <mpm@selenic.com>,
       Alexey Dobriyan <adobriyan@gmail.com>
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Date: Wed, 11 Mar 2009 10:17:58 +0900 (JST)
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> Fix kpf_copy_bit(src,dst) to be kpf_copy_bit(dst,src) to match the
> actual call patterns, e.g. kpf_copy_bit(kflags, KPF_LOCKED, PG_locked).
> 
> This misplacement of src/dst only affected reporting of PG_writeback,
> PG_reclaim and PG_buddy. For others kflags==uflags so not affected.
> 
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
> 
> This is a tested and trivial no-side-effect fix.
> I'd suggest it for 2.6.29-rc7 and 2.6.28.X kernels.
> 
> diff --git a/fs/proc/page.c b/fs/proc/page.c
> index 2d13451..e998383 100644
> --- a/fs/proc/page.c
> +++ b/fs/proc/page.c
> @@ -80,7 +80,7 @@ static const struct file_operations proc_kpagecount_operations = {
>  #define KPF_RECLAIM    9
>  #define KPF_BUDDY     10
>  
> -#define kpf_copy_bit(flags, srcpos, dstpos) (((flags >> srcpos) & 1) << dstpos)
> +#define kpf_copy_bit(flags, dstpos, srcpos) (((flags >> srcpos) & 1) << dstpos)

Good catch! :)
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>


but don't worry. the number of this interface user is very few.