<div dir="ltr"><div>Hi, list<br><br></div>When I umount a DRBD device used by a DRBD client, the &#39;umount&#39; program hang, and I got the following call trace:<br><br>```<br>[28076.944996] XFS (drbd100): Unmounting Filesystem<br>[28198.933553] drbd web: State change failed: Device is held open by someone<br>[28198.935451] drbd web: Failed: role( Primary -&gt; Secondary )<br>[28200.828646] INFO: task umount:21558 blocked for more than 120 seconds.<br>[28200.830496] &quot;echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs&quot; disables this message.<br>[28200.831238] umount          D ffff8801379fc890     0 21558  21271 0x00000084<br>[28200.831253]  ffff8800a164fd90 0000000000000082 ffff880136345c00 ffff8800a164ffd8<br>[28200.831282]  ffff8800a164ffd8 ffff8800a164ffd8 ffff880136345c00 ffff8801379fc880<br>[28200.831284]  ffff8800a1337d10 ffff8801379fc8c0 ffff8801379fc8e8 ffff8801379fc890<br>[28200.831289] Call Trace:<br>[28200.831321]  [&lt;ffffffff8163a909&gt;] schedule+0x29/0x70<br>[28200.831516]  [&lt;ffffffffa023fc41&gt;] xfs_ail_push_all_sync+0xc1/0x110 [xfs]<br>[28200.831554]  [&lt;ffffffff810a6ae0&gt;] ? wake_up_atomic_t+0x30/0x30<br>[28200.831572]  [&lt;ffffffffa022ab08&gt;] xfs_unmountfs+0x68/0x190 [xfs]<br>[28200.831584]  [&lt;ffffffffa022b5eb&gt;] ? xfs_mru_cache_destroy+0x6b/0x90 [xfs]<br>[28200.831597]  [&lt;ffffffffa022d9c2&gt;] xfs_fs_put_super+0x32/0x90 [xfs]<br>[28200.831621]  [&lt;ffffffff811e0ab6&gt;] generic_shutdown_super+0x56/0xe0<br>[28200.831623]  [&lt;ffffffff811e0f07&gt;] kill_block_super+0x27/0x70<br>[28200.831625]  [&lt;ffffffff811e1249&gt;] deactivate_locked_super+0x49/0x60<br>[28200.831627]  [&lt;ffffffff811e1846&gt;] deactivate_super+0x46/0x60<br>[28200.831632]  [&lt;ffffffff811fe785&gt;] mntput_no_expire+0xc5/0x120<br>[28200.831635]  [&lt;ffffffff811ff8bf&gt;] SyS_umount+0x9f/0x3c0<br>[28200.831642]  [&lt;ffffffff81645909&gt;] system_call_fastpath+0x16/0x1b<br>[28320.831678] INFO: task umount:21558 blocked for more than 120 seconds.<br>[28320.833583] &quot;echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs&quot; disables this message.<br>[28320.834275] umount          D ffff8801379fc890     0 21558  21271 0x00000084<br>[28320.834286]  ffff8800a164fd90 0000000000000082 ffff880136345c00 ffff8800a164ffd8<br>[28320.834290]  ffff8800a164ffd8 ffff8800a164ffd8 ffff880136345c00 ffff8801379fc880<br>[28320.834292]  ffff8800a1337d10 ffff8801379fc8c0 ffff8801379fc8e8 ffff8801379fc890<br>[28320.834295] Call Trace:<br>[28320.834349]  [&lt;ffffffff8163a909&gt;] schedule+0x29/0x70<br>[28320.834653]  [&lt;ffffffffa023fc41&gt;] xfs_ail_push_all_sync+0xc1/0x110 [xfs]<br>[28320.834688]  [&lt;ffffffff810a6ae0&gt;] ? wake_up_atomic_t+0x30/0x30<br>[28320.834708]  [&lt;ffffffffa022ab08&gt;] xfs_unmountfs+0x68/0x190 [xfs]<br>[28320.834724]  [&lt;ffffffffa022b5eb&gt;] ? xfs_mru_cache_destroy+0x6b/0x90 [xfs]<br>[28320.834752]  [&lt;ffffffffa022d9c2&gt;] xfs_fs_put_super+0x32/0x90 [xfs]<br>[28320.834771]  [&lt;ffffffff811e0ab6&gt;] generic_shutdown_super+0x56/0xe0<br>[28320.834775]  [&lt;ffffffff811e0f07&gt;] kill_block_super+0x27/0x70<br>[28320.834780]  [&lt;ffffffff811e1249&gt;] deactivate_locked_super+0x49/0x60<br>[28320.834783]  [&lt;ffffffff811e1846&gt;] deactivate_super+0x46/0x60<br>[28320.834791]  [&lt;ffffffff811fe785&gt;] mntput_no_expire+0xc5/0x120<br>[28320.834795]  [&lt;ffffffff811ff8bf&gt;] SyS_umount+0x9f/0x3c0<br>[28320.834803]  [&lt;ffffffff81645909&gt;] system_call_fastpath+0x16/0x1<br>```<br clear="all"><div><div><div><div><br></div><div>Before umount hang, I did the following steps:<br></div><div>1. mount the drbd device at DRBD client (pure client) node;<br></div><div>2. poweroff 2 of the 3 nodes that contains the resource for the DRBD client above<br></div><div>3. write to a file under the mount point at step 1<br></div><div>4. umount the drbd device at step 1    &lt;= umount hang<br></div><div><br></div><div>My environment:<br># cat /etc/centos-release<br>CentOS Linux release 7.2.1511 (Core)<br># rpm -qa | grep drbd<br>kmod-drbd-9.0.1_3.10.0_327-1.el7.centos.x86_64<br>drbdmanage-0.99.4-1.noarch<br>drbd-utils-8.9.11-1.el7.centos.x86_64<br></div><div><br></div><div>The call trace doesn&#39;t show anything obviously related to DRBD 9.  But just in case.<br></div><div><br>-- <br><div class="gmail_signature">Thanks,<br>Li Qun<br></div>
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