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From: Wei Yang <richardw.yang@linux.intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <zwisler@kernel.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH] libnvdimm, pfn: not allocate nd_pfn->pfn_sb if already allocated
Date: Fri, 18 Jan 2019 13:03:33 +0800	[thread overview]
Message-ID: <20190118050333.GA4233@richard> (raw)
In-Reply-To: <CAPcyv4jOA-S=Z-0mCUW7d4+6gwHNEe1egaFrbyNq5UJL7Uz=Ow@mail.gmail.com>

On Thu, Jan 17, 2019 at 08:31:56PM -0800, Dan Williams wrote:
>On Thu, Jan 17, 2019 at 7:36 PM Wei Yang <richardw.yang@linux.intel.com> wrote:
>>
>> In current implementation, we might re-allocate nd_pfn->pfn_sb.
>>
>> For example:
>>
>>     nd_dax_probe()
>>         nd_pfn->pfn_sb = devm_kzalloc()
>>
>>     dax_pmem_probe()
>>         nvdimm_setup_pfn()
>>             nd_pfn_init()
>>                 nd_pfn->pfn_sb = devm_kzalloc()
>>
>> This patch checks nd_pfn->pfn_sb before allocating it in nd_pfn_init().
>
>Ugh, this patch is unfortunately uncovering a deeper problem.
>nvdimm_setup_pfn() should not be calling nd_pfn_init(). This
>effectively is always re-initializing the info-block, benign but
>unnecessary. Instead it needs to be using nd_pfn_validate() followed
>by an __nvdimm_setup_pfn() in the dax_pmem_probe() path.
>
>Good find!

So we should fix this like:

dax_pmem_probe()
    nd_pfn_validate()
    __nvdimm_setup_pfn()

Is my understanding correct?

-- 
Wei Yang
Help you, Help me
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
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  reply	other threads:[~2019-01-18  5:03 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-18  3:35 [PATCH] libnvdimm, pfn: not allocate nd_pfn->pfn_sb if already allocated Wei Yang
2019-01-18  4:31 ` Dan Williams
2019-01-18  5:03   ` Wei Yang [this message]
2019-01-18  5:05     ` Dan Williams
2019-01-18  7:31       ` Wei Yang
2019-01-18  8:38         ` Dan Williams
2019-01-18 18:59           ` Dan Williams
2019-01-21  0:50             ` Wei Yang
2019-01-21  3:28               ` Dan Williams
2019-01-21  0:24           ` Wei Yang

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