On Tue, 20 May 2014, Kenny Simpson wrote: > I might need a gentle nudge with a clue stick... > checking against latest git tree it looks as though most common > filesystem types do support remap_file_pages. > > I just wrote a simple test case and it worked on my 3.13-based ubuntu > 14.04 system on an ext4 filesystem.
It is all very confusing, yes. When Kirill said disk-backed files don't support remap_file_pages since commit 3ee6dafc677a, he was meaning that that they do not support it with a special nonlinear vma; but the remap_file_pages syscall emulates the layout for them with separate linear vmas instead. Confusingly, these filesystems opt in to this emulation by pointing their remap_pages method to generic_file_remap_pages - code which is then never used for them! tmpfs is the only filesystem (having no page_mkwrite) which actually passes through that code. You can understand why there's some enthusiasm for cleaning this up :) Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
