On Thu 08-09-16 14:47:08, Ross Zwisler wrote: > 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 Hum, nothing unusual in there. I've tried reproducing on a local SLE11 SP3 machine (which is from about the same time) but everything works as expected there. Shrug... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
