Xen 4 snapshot problem

[Valtteri Kiviniemi <mailinglists@dataproof.fi>]

Hi,

I am having some problems with Xen 4 (2.6.31.13) and lvm-snapshots. I 
have a snapshot-script running once a night. The snapshots are created 
succesfully and all the data is accessible. However, some times the 
snapshot creation gives errors in dmesg, but it still finishes 
succesfully. I had problems previously on Xen 3.4's 2.6.18.8 kernel 
where the lvcreate command just stuck. I was instructed to test Xen 4 
and the latest pv_ops kernel to see if it works better. Is there still 
some bug related to creating lvm snapshots?

Server is running latest Xen downloaded from xen.org and manually 
compiled. Distro is debian lenny.

Log:

attempt to access beyond end of device
dm-0: rw=0, want=209715144, limit=41943040
Buffer I/O error on device dm-0, logical block 26214392
EXT4-fs (dm-0): barriers enabled
kjournald2 starting: pid 2572, dev dm-0:8, commit interval 5 seconds
EXT4-fs (dm-0): internal journal on dm-0:8
EXT4-fs (dm-0): delayed allocation enabled
EXT4-fs: file extents enabled
EXT4-fs: mballoc enabled
EXT4-fs (dm-0): ext4_orphan_cleanup: deleting unreferenced inode 265279
EXT4-fs (dm-0): 1 orphan inode deleted
EXT4-fs (dm-0): recovery complete
EXT4-fs (dm-0): mounted filesystem with ordered data mode
mount: page allocation failure. order:5, mode:0xc0d0
Pid: 3178, comm: mount Not tainted 2.6.31.13-dom0 #1
Call Trace:
  [<ffffffff8106b539>] ? __alloc_pages_nodemask+0x507/0x54e
  [<ffffffff8106b5e9>] ? __get_free_pages+0x12/0x4f
  [<ffffffff8110562d>] ? ext4_mb_init+0x34c/0x425
  [<ffffffff810f976c>] ? ext4_fill_super+0x1b4c/0x1fe4
  [<ffffffff811a5177>] ? snprintf+0x44/0x4c
  [<ffffffff81391274>] ? __down_write_nested+0x34/0xa9
  [<ffffffff8100e21f>] ? xen_restore_fl_direct_end+0x0/0x1
  [<ffffffff8100db7d>] ? xen_force_evtchn_callback+0x9/0xa
  [<ffffffff8100e232>] ? check_events+0x12/0x20
  [<ffffffff81090326>] ? get_sb_bdev+0x111/0x159
  [<ffffffff810f7c20>] ? ext4_fill_super+0x0/0x1fe4
  [<ffffffff8108f456>] ? vfs_kern_mount+0x4f/0x95
  [<ffffffff8108f4ef>] ? do_kern_mount+0x43/0xe1
  [<ffffffff8100e232>] ? check_events+0x12/0x20
  [<ffffffff810a3415>] ? do_mount+0x716/0x782
  [<ffffffff810a3506>] ? sys_mount+0x85/0xcf
  [<ffffffff81011942>] ? system_call_fastpath+0x16/0x1b
Mem-Info:
DMA per-cpu:
CPU    0: hi:    0, btch:   1 usd:   0
CPU    1: hi:    0, btch:   1 usd:   0
CPU    2: hi:    0, btch:   1 usd:   0
CPU    3: hi:    0, btch:   1 usd:   0
DMA32 per-cpu:
CPU    0: hi:  186, btch:  31 usd:   0
CPU    1: hi:  186, btch:  31 usd:   0
CPU    2: hi:  186, btch:  31 usd:   0
CPU    3: hi:  186, btch:  31 usd:   0
Active_anon:12622 active_file:75787 inactive_anon:12687
  inactive_file:51082 unevictable:5 dirty:7507 writeback:17 unstable:0
  free:3836 slab:76527 mapped:1129 pagetables:843 bounce:0
DMA free:4000kB min:52kB low:64kB high:76kB active_anon:0kB 
inactive_anon:84kB a 
                                                 ctive_file:5440kB 
inactive_file:2832kB unevictable:0kB present:13756kB pages_sca 
 
                    nned:0 all_unreclaimable? no
lowmem_reserve[]: 0 994 994 994
DMA32 free:11344kB min:4004kB low:5004kB high:6004kB active_anon:50488kB 
inactiv 
                                    e_anon:50664kB active_file:297708kB 
inactive_file:201496kB unevictable:20kB pres 
 
  ent:1018080kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
DMA: 254*4kB 1*8kB 2*16kB 0*32kB 8*64kB 5*128kB 5*256kB 1*512kB 0*1024kB 
0*2048k 
                                    B 0*4096kB = 4000kB
DMA32: 1510*4kB 149*8kB 217*16kB 10*32kB 1*64kB 2*128kB 0*256kB 0*512kB 
0*1024kB 
                                      0*2048kB 0*4096kB = 11344kB
127182 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap  = 0kB
Total swap = 0kB
262144 pages RAM
23192 pages reserved
127122 pages shared
111804 pages non-shared