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From: Miaohe Lin <linmiaohe@huawei.com>
To: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: <akpm@linux-foundation.org>, <naoya.horiguchi@nec.com>,
	<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: memory-failure: fix potential page refcnt leak in memory_failure()
Date: Mon, 3 Jul 2023 19:27:25 +0800	[thread overview]
Message-ID: <1e8ff9bf-c81b-9c39-9f44-2f82efcd36ec@huawei.com> (raw)
In-Reply-To: <20230703063713.GA3012709@ik1-406-35019.vs.sakura.ne.jp>

On 2023/7/3 14:37, Naoya Horiguchi wrote:
> On Sat, Jul 01, 2023 at 03:28:37PM +0800, Miaohe Lin wrote:
>> put_ref_page() is not called to drop extra refcnt when comes from madvise
>> in the case pfn is valid but pgmap is NULL leading to page refcnt leak.
> 
> Is this test scenario realistic one?  I don't think that we can call madvise() for
> such a device memory page.  If this is the case, this issue can be thought as
> potentioal one (so no need to send to stable). 

This is a theoretical problem. If pagemap can ever be NULL after page refcnt is increased, this
would occur. I think it's not needed to send to stable too.

> 
>>
>> Fixes: 1e8aaedb182d ("mm,memory_failure: always pin the page in madvise_inject_error")
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> 
> Anyway, the patch looks good to me. Thanks you.
> 
> Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Thanks for your review and comment.


      reply	other threads:[~2023-07-03 11:27 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-01  7:28 Miaohe Lin
2023-07-03  6:37 ` Naoya Horiguchi
2023-07-03 11:27   ` Miaohe Lin [this message]

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