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From: Minchan Kim <minchan@kernel.org>
To: zhouxianrong <zhouxianrong@tom.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	ngupta@vflare.org, sergey.senozhatsky.work@gmail.com,
	zhouxianrong <zhouxianrong@huawei.com>
Subject: Re: [PATCH] zsmalloc: fix linking bug in init_zspage
Date: Mon, 13 Aug 2018 15:05:49 +0900	[thread overview]
Message-ID: <20180813060549.GB64836@rodete-desktop-imager.corp.google.com> (raw)
In-Reply-To: <20180810002817.2667-1-zhouxianrong@tom.com>

Hi,

On Thu, Aug 09, 2018 at 08:28:17PM -0400, zhouxianrong wrote:
> From: zhouxianrong <zhouxianrong@huawei.com>
> 
> The last partial object in last subpage of zspage should not be linked
> in allocation list. Otherwise it could trigger BUG_ON explicitly at
> function zs_map_object. But it happened rarely.

Could you be more specific? What case did you see the problem?
Is it a real problem or one founded by review?

Thanks.

> 
> Signed-off-by: zhouxianrong <zhouxianrong@huawei.com>
> ---
>  mm/zsmalloc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 8d87e973a4f5..24dd8da0aa59 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1040,6 +1040,8 @@ static void init_zspage(struct size_class *class, struct zspage *zspage)
>  			 * Reset OBJ_TAG_BITS bit to last link to tell
>  			 * whether it's allocated object or not.
>  			 */
> +			if (off > PAGE_SIZE)
> +				link -= class->size / sizeof(*link);
>  			link->next = -1UL << OBJ_TAG_BITS;
>  		}
>  		kunmap_atomic(vaddr);
> -- 
> 2.13.6
> 

  reply	other threads:[~2018-08-13  6:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-10  0:28 [PATCH] zsmalloc: fix linking bug in init_zspage zhouxianrong
2018-08-13  6:05 ` Minchan Kim [this message]
2018-08-13 10:55   ` Sergey Senozhatsky
2018-08-14  0:24     ` Minchan Kim
2018-08-14  0:51       ` Sergey Senozhatsky
     [not found]       ` <1784999539.213028.1534378242020.JavaMail.root@rz-web2>
2018-08-16  3:46         ` Minchan Kim
  -- strict thread matches above, loose matches on Subject: below --
2018-08-09 13:53 zhouxianrong
2018-08-09 14:41 ` Vlastimil Babka

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