Hello,
in my SLES 11 with custom kernel 3.10.9, I insert a GFS2 volume (iSCSI).
It works fine but after a while with data access in the LUN, following error appeared.


[ 6240.651154] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 6240.651159] httpd D ffff88007f619c58 0 19957 19893 0x00000000
[ 6240.651170] ffff88007653f9d8 0000000000000086 0000000000000000 ffff880036c27bc0
[ 6240.651180] 0000000000000000 0000000000000000 ffff88007653f9a8 ffff88007653e010
[ 6240.651189] ffff88007653e000 ffff88007653e010 ffff88007653e000 ffff88007653e000
[ 6240.651208] Call Trace:
[ 6240.651222] [<ffffffff81184f8d>] ? find_get_page+0x4d/0xc0
[ 6240.651229] [<ffffffff811852a5>] ? find_lock_page+0x25/0x80
[ 6240.651235] [<ffffffff811864ba>] ? find_or_create_page+0x3a/0xa0
[ 6240.651242] [<ffffffff81098163>] ? default_spin_lock_flags+0x13/0x30
[ 6240.651249] [<ffffffff818cf4f4>] schedule+0x24/0x70
[ 6240.651268] [<ffffffffa05c9dc9>] gfs2_glock_holder_wait+0x9/0x10 [gfs2]
[ 6240.651274] [<ffffffff818cd41a>] __wait_on_bit+0x5a/0x90
[ 6240.651287] [<ffffffffa05c9dc0>] ? gfs2_glock_demote_wait+0x10/0x10 [gfs2]
[ 6240.651301] [<ffffffffa05c9dc0>] ? gfs2_glock_demote_wait+0x10/0x10 [gfs2]
[ 6240.651306] [<ffffffff818cd4c4>] out_of_line_wait_on_bit+0x74/0x90
[ 6240.651314] [<ffffffff810d6430>] ? autoremove_wake_function+0x40/0x40
[ 6240.651327] [<ffffffffa05cbcac>] ? gfs2_glock_put+0x4c/0x260 [gfs2]
[ 6240.651341] [<ffffffffa05ca7de>] gfs2_glock_wait+0x3e/0x80 [gfs2]
[ 6240.651355] [<ffffffffa05cdc70>] gfs2_glock_nq+0x2f0/0x3d0 [gfs2]
[ 6240.651372] [<ffffffffa05d9851>] gfs2_glock_nq_init+0x21/0x40 [gfs2]
[ 6240.651417] [<ffffffffa05da371>] gfs2_permission+0xf1/0x100 [gfs2]
[ 6240.651434] [<ffffffffa05d9849>] ? gfs2_glock_nq_init+0x19/0x40 [gfs2]
[ 6240.651441] [<ffffffff811fbad6>] __inode_permission+0x46/0xf0
[ 6240.651447] [<ffffffff811fbbbd>] inode_permission+0x3d/0x60
[ 6240.651453] [<ffffffff811fed4d>] link_path_walk+0x46d/0x9b0
[ 6240.651459] [<ffffffff811fb525>] ? lock_rcu_walk+0x15/0x20
[ 6240.651465] [<ffffffff811ff3d3>] path_lookupat+0x53/0x8a0
[ 6240.651471] [<ffffffff811fbf03>] ? getname_flags+0x53/0x1b0
[ 6240.651477] [<ffffffff811ffc53>] filename_lookup+0x33/0xd0
[ 6240.651483] [<ffffffff81200dab>] user_path_at_empty+0x7b/0xb0
[ 6240.651490] [<ffffffff8109d91e>] ? bad_area_nosemaphore+0xe/0x10
[ 6240.651496] [<ffffffff818d4fe8>] ? __do_page_fault+0x2d8/0x540
[ 6240.651502] [<ffffffff81200dec>] user_path_at+0xc/0x10
[ 6240.651507] [<ffffffff811f5da1>] vfs_fstatat+0x51/0xb0
[ 6240.651512] [<ffffffff811f5e69>] vfs_lstat+0x19/0x20
[ 6240.651517] [<ffffffff811f5e8f>] SyS_newlstat+0x1f/0x50
[ 6240.651522] [<ffffffff818d5259>] ? do_page_fault+0x9/0x10
[ 6240.651529] [<ffffffff818d1b88>] ? page_fault+0x28/0x30
[ 6240.651535] [<ffffffff818d8f6d>] system_call_fastpath+0x1a/0x1f

or this

[ 2880.650146] INFO: task httpd:3295 blocked for more than 480 seconds.
[ 2880.650152] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 2880.650154] httpd D ffff88007f616c58 0 3295 3253 0x00000000
[ 2880.650161] ffff880062735c78 0000000000000082 ffff880062734000 ffff88003737a040
[ 2880.650167] 0000000000000000 00000000000080d0 ffff8800448dd3b0 ffff880062734010
[ 2880.650172] ffff880062734000 ffff880062734010 ffff880062734000 ffff880062734000
[ 2880.650177] Call Trace:
[ 2880.650207] [<ffffffffa05d218e>] ? gfs2_holder_uninit+0x1e/0x40 [gfs2]
[ 2880.650218] [<ffffffffa05d2539>] ? gfs2_glock_dq_uninit+0x19/0x20 [gfs2]
[ 2880.650231] [<ffffffffa05dbed5>] ? gfs2_open+0xe5/0x160 [gfs2]
[ 2880.650240] [<ffffffff81098163>] ? default_spin_lock_flags+0x13/0x30
[ 2880.650251] [<ffffffff818cf4f4>] schedule+0x24/0x70
[ 2880.650261] [<ffffffffa05cfdc9>] gfs2_glock_holder_wait+0x9/0x10 [gfs2]
[ 2880.650265] [<ffffffff818cd41a>] __wait_on_bit+0x5a/0x90
[ 2880.650275] [<ffffffffa05cfdc0>] ? gfs2_glock_demote_wait+0x10/0x10 [gfs2]
....


An Apache web server runs in the LUN and it stops working.

Does anybody have some hints or tricks ?

Best regards
B.-D.