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From: Vitaly Wool <vitalywool@gmail.com>
Date: Mon, 17 Oct 2016 14:03:28 +0200
Message-ID: <CAMJBoFMcnH3ZPQpG=oAjD=K64O7MX_BdFvHvccvgCV4nFSfxXA@mail.gmail.com>
Subject: Re: [PATCH v2] z3fold: fix the potential encode bug in encod_handle
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To: zhong jiang <zhongjiang@huawei.com>
Cc: Dave Chinner <david@fromorbit.com>, Seth Jennings <sjenning@redhat.com>, Dan Streetman <ddstreet@ieee.org>, Andrew Morton <akpm@linux-foundation.org>, Michal Hocko <mhocko@kernel.org>, Vlastimil Babka <vbabka@suse.cz>, LKML <linux-kernel@vger.kernel.org>, Linux-MM <linux-mm@kvack.org>

Hi Zhong Jiang,

On Mon, Oct 17, 2016 at 3:58 AM, zhong jiang <zhongjiang@huawei.com> wrote:
> Hi,  Vitaly
>
> About the following patch,  is it right?
>
> Thanks
> zhongjiang
> On 2016/10/13 12:02, zhongjiang wrote:
>> From: zhong jiang <zhongjiang@huawei.com>
>>
>> At present, zhdr->first_num plus bud can exceed the BUDDY_MASK
>> in encode_handle, it will lead to the the caller handle_to_buddy
>> return the error value.
>>
>> The patch fix the issue by changing the BUDDY_MASK to PAGE_MASK,
>> it will be consistent with handle_to_z3fold_header. At the same time,
>> change the BUDDY_MASK to PAGE_MASK in handle_to_buddy is better.

are you seeing problems with the existing code? first_num should wrap around
BUDDY_MASK and this should be ok because it is way bigger than the number
of buddies.

~vitaly

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