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Date: Sat, 6 Feb 2016 16:14:07 +0800
From: zhong jiang <zhongjiang@huawei.com>
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Subject: Have some confusion about the pfn_valid() ?
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Hi

In my opinion, pfn_valid() is meant to be able to tell if a given PFN has valid
section, and That section can contain corresponding mem_map. but, the section can
be has holes, the corresponding mem_map also be allcoated, resulting in treating
the PFN as valid incorrect.

what's problem for the interpretation of the above?