Messages in this thread | | | Subject | Re: [PATCH] mm: Fix mmap MAP_POPULATE for DAX pmd mapping | From | Dave Hansen <> | Date | Wed, 2 Dec 2015 14:09:10 -0800 |
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On 12/02/2015 02:03 PM, Dan Williams wrote: >>> >> Is pfn_valid() a reliable check? It seems to be based on a max_pfn >>> >> per node... what happens when pmem is located below that point. I >>> >> haven't been able to convince myself that we won't get false >>> >> positives, but maybe I'm missing something. >> > >> > With sparsemem at least, it makes sure that you're looking at a valid >> > _section_. See the pfn_valid() at ~include/linux/mmzone.h:1222. > At a minimum we would need to add "depends on SPARSEMEM" to "config FS_DAX_PMD".
Yeah, it seems like an awful layering violation. But, sparsemem is turned on everywhere (all the distros/users) that we care about, as far as I know.
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