This bug exists both in mainline and ext4-patch-queue. Procedures to reproduce it: 1. mkfs.ext4dev -I 256 -b 4096 -O extents /dev/sdb1 2. mount -t ext4dev -o delalloc /dev/sdb1 mnt_point/ 3. run ffsb until filesystem is full and ffsb exits with failure 4. umount mnt_point And then umount stuck at D state. The output of ps: 3873 ? D< 0:07 [kjournald2] 3880 ? D 0:00 [pdflush] 3885 ? S 0:00 [pdflush] 3944 ? S 0:00 [pdflush] 3957 ? S 0:00 [pdflush] 3962 ? S 0:00 [pdflush] 3974 ? S 0:00 [pdflush] 3975 ? S 0:00 [pdflush] 3979 pts/1 D+ 0:01 umount mnt_point dmesg: EXT4-fs: barriers enabled kjournald2 starting. Commit interval 5 seconds EXT4 FS on sdb1, internal journal on sdb1:8 EXT4-fs: mounted filesystem with ordered data mode. EXT4-fs: delayed allocation enabled EXT4-fs: file extents enabled EXT4-fs: mballoc enabled ffsb[3888]: segfault at 8 ip 0000003878832dc7 sp 00000000425f5fa0 error 4 in libc-2.5.so[3878800000+146000] INFO: task pdflush:3880 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. pdflush D ffff88013c6eb700 0 3880 2 ffff88009a623df0 0000000000000046 0000000000000000 ffffffff80254c20 ffff8800bfa63040 ffff8800bfa63040 ffff88013faf3040 ffff8800bfa63398 00000002bfa63040 000000010009baab ffffffffffffffff ffffffffffffffff Call Trace: [<ffffffff80254c20>] __lock_acquire+0x6ad/0x716 [<ffffffff8049e9de>] __down_read+0x7e/0x96 [<ffffffff802a32a6>] sync_supers+0x3f/0xb3 [<ffffffff802a32a6>] sync_supers+0x3f/0xb3 [<ffffffff8027d50e>] pdflush+0x0/0x207 [<ffffffff8027d0bf>] wb_kupdate+0x2d/0x10d [<ffffffff8027d50e>] pdflush+0x0/0x207 [<ffffffff8027d50e>] pdflush+0x0/0x207 [<ffffffff8027d664>] pdflush+0x156/0x207 [<ffffffff8027d092>] wb_kupdate+0x0/0x10d [<ffffffff8024961b>] kthread+0x47/0x74 [<ffffffff8049ea30>] trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff8020cea9>] child_rip+0xa/0x11 [<ffffffff8020c4df>] restore_args+0x0/0x30 [<ffffffff802495d4>] kthread+0x0/0x74 [<ffffffff8020ce9f>] child_rip+0x0/0x11 1 lock held by pdflush/3880: #0: (&type->s_umount_key#21){----}, at: [<ffffffff802a32a6>] sync_supers+0x3f/0xb3 INFO: task pdflush:3880 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. pdflush D ffff88013c6eb700 0 3880 2 ffff88009a623df0 0000000000000046 0000000000000000 ffffffff80254c20 ffff8800bfa63040 ffff8800bfa63040 ffff88013faf3040 ffff8800bfa63398 00000002bfa63040 000000010009baab ffffffffffffffff ffffffffffffffff Call Trace: [<ffffffff80254c20>] __lock_acquire+0x6ad/0x716 [<ffffffff8049e9de>] __down_read+0x7e/0x96 [<ffffffff802a32a6>] sync_supers+0x3f/0xb3 [<ffffffff802a32a6>] sync_supers+0x3f/0xb3 [<ffffffff8027d50e>] pdflush+0x0/0x207 [<ffffffff8027d0bf>] wb_kupdate+0x2d/0x10d [<ffffffff8027d50e>] pdflush+0x0/0x207 [<ffffffff8027d50e>] pdflush+0x0/0x207 [<ffffffff8027d664>] pdflush+0x156/0x207 [<ffffffff8027d092>] wb_kupdate+0x0/0x10d [<ffffffff8024961b>] kthread+0x47/0x74 [<ffffffff8049ea30>] trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff8020cea9>] child_rip+0xa/0x11 [<ffffffff8020c4df>] restore_args+0x0/0x30 [<ffffffff802495d4>] kthread+0x0/0x74 [<ffffffff8020ce9f>] child_rip+0x0/0x11 1 lock held by pdflush/3880: #0: (&type->s_umount_key#21){----}, at: [<ffffffff802a32a6>] sync_supers+0x3f/0xb3 -- 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