On Tue, Sep 06, 2016 at 05:06:20PM +0200, Jan Kara wrote: > On Thu 01-09-16 20:57:38, Ross Zwisler wrote: > > On Wed, Aug 31, 2016 at 04:44:47PM +0800, Xiao Guangrong wrote: > > > On 08/31/2016 01:09 AM, Dan Williams wrote: > > > > > > > > Can you post your exact reproduction steps? This test is not failing for me. > > > > > > > > > > Sure. > > > > > > 1. make the guest kernel based on your tree, the top commit is > > > 10d7902fa0e82b (dax: unmap/truncate on device shutdown) and > > > the config file can be found in this thread. > > > > > > 2. add guest kernel command line: memmap=6G!10G > > > > > > 3: start the guest: > > > x86_64-softmmu/qemu-system-x86_64 -machine pc,nvdimm --enable-kvm \ > > > -smp 16 -m 32G,maxmem=100G,slots=100 /other/VMs/centos6.img -monitor stdio > > > > > > 4: in guest: > > > mkfs.ext4 /dev/pmem0 > > > mount -o dax /dev/pmem0 /mnt/pmem/ > > > echo > /mnt/pmem/xxx > > > ./mmap /mnt/pmem/xxx > > > ./read /mnt/pmem/xxx > > > > > > The source code of mmap and read has been attached in this mail. > > > > > > Hopefully, you can detect the error triggered by read test. > > > > > > Thanks! > > > > Okay, I think I've isolated this issue. Xiao's VM was an old CentOS 6 system, > > and for some reason ext4+DAX with the old tools found in that VM fails. I was > > able to reproduce this failure with a freshly installed CentOS 6.8 VM. > > > > You can see the failure with his tests, or perhaps more easily with this > > series of commands: > > > > # mkfs.ext4 /dev/pmem0 > > # mount -o dax /dev/pmem0 /mnt/pmem/ > > # touch /mnt/pmem/x > > # md5sum /mnt/pmem/x > > md5sum: /mnt/pmem/x: Bad address > > > > This sequence of commands works fine in the old CentOS 6 system if you use XFS > > instead of ext4, and it works fine with both ext4 and XFS in CentOS 7 and > > with recent versions of Fedora. > > > > I've added the ext4 folks to this mail in case they care, but my guess is that > > the tools in CentOS 6 are so old that it's not worth worrying about. For > > reference, the kernel in CentOS 6 is based on 2.6.32. :) DAX was introduced > > in v4.0. > > Hum, can you post 'dumpe2fs -h /dev/pmem0' output from that system when the > md5sum fails? Because the only idea I have is that mkfs.ext4 in CentOS 6 > creates the filesystem with a different set of features than more recent > e2fsprogs and so we hit some untested path... Sure, here's the output: # dumpe2fs -h /dev/pmem0 dumpe2fs 1.41.12 (17-May-2010) Filesystem volume name: <none> Last mounted on: /mnt/pmem Filesystem UUID: 4cd8a836-cc54-4c59-ae0a-4a26bab0f8bc Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize Filesystem flags: signed_directory_hash Default mount options: (none) Filesystem state: clean Errors behavior: Continue Filesystem OS type: Linux Inode count: 1048576 Block count: 4194304 Reserved block count: 209715 Free blocks: 4084463 Free inodes: 1048565 First block: 0 Block size: 4096 Fragment size: 4096 Reserved GDT blocks: 1023 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 8192 Inode blocks per group: 512 RAID stride: 1 Flex block group size: 16 Filesystem created: Thu Sep 8 14:45:31 2016 Last mount time: Thu Sep 8 14:45:39 2016 Last write time: Thu Sep 8 14:45:39 2016 Mount count: 1 Maximum mount count: 21 Last checked: Thu Sep 8 14:45:31 2016 Check interval: 15552000 (6 months) Next check after: Tue Mar 7 13:45:31 2017 Lifetime writes: 388 MB Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 256 Required extra isize: 28 Desired extra isize: 28 Journal inode: 8 Default directory hash: half_md4 Directory Hash Seed: 19cad581-c46a-4212-bfa0-d527ff55db49 Journal backup: inode blocks Journal features: (none) Journal size: 128M Journal length: 32768 Journal sequence: 0x00000002 Journal start: 1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
