On Tue, Feb 7, 2017 at 7:51 PM, Xiong Zhou <[email protected]> wrote: > On Fri, Jan 20, 2017 at 12:40:07PM +0800, Xiong Zhou wrote: >> Hi, >> >> At first, I am not sure whether this is an issue. >> >> mmap a file in a DAX mountpoint, open another file >> in a non-DAX mountpoint with O_DIRECT, write the >> mapped area to the other file. >> >> This write Success on pmem ramdisk(memmap=2G!20G like) >> This write Fail(Bad address) on nvdimm pmem devices. >> This write Fail(Bad address) on brd based ramdisk. >> >> If we skip the O_DIRECT flag, all tests pass. >> >> If we write from DAX to DAX, all tests pass. >> If we write from non-DAX to DAX, all tests pass. >> > snip.. > > To falloc instead of pwrite while initiating test files, > ( Thanks Ross! :) > the write call returned success, however the following > read back to mmaped area FAILED the same way: > > return (Bad address) on raw-mode nvdimm device; > return (Success) on memory-mode nvdimm device; > return (Bad address) on brd based ramdisk. > > Also, this only happends with O_DIRECT flag on. > > This smells like an issue to me, still looking into why > read can't get that page.. >
Why does it smell like an issue? Any path that calls get_user_pages() and a DAX mmap range will fail without "memory" mode. I'm of the opinion that we should disable DAX altogether for raw-mode. _______________________________________________ Linux-nvdimm mailing list [email protected] https://lists.01.org/mailman/listinfo/linux-nvdimm
