Matthew Wilcox wrote on Tue, Sep 03, 2019: > > What I'd like to know is: > > - we know (assuming the other side isn't too bugged, but if it is we're > > fucked up anyway) exactly what huge-page-sized physical memory range has > > been mapped on the other side, is there a way to manually gather the > > pages corresponding and merge them into a huge page? > > You're using the word 'page' here, but I suspect what you really mean is > "pfn" or "pte". As you've described it, it doesn't matter what data structure > Linux is using for the memory, since Linux doesn't know about the memory. Correct, we're already using vmf_insert_pfn > We have vmf_insert_pfn_pmd() which is designed to be called from your > ->huge_fault handler. See dev_dax_huge_fault() -> __dev_dax_pmd_fault() > for an example. It's a fairly new mechanism, so I don't think it's > popular with device drivers yet. > > All you really need is the physical address of the memory to make this work. Great; I'm not sure how I had missed the pmd variant here. It's even been around for long enough to be available on our "old" el7 kernels so I'll be able to test this quickly. Thanks! -- Dominique
