From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: 2.6.35 causes deadlock when snapshotting root lv Date: Fri, 18 Jun 2010 14:23:25 -0500 Message-ID: <4C1BC7AD.1060900@sandeen.net> References: <4C1A2839.5010407@cfl.rr.com> <20100617142731.GA10071@redhat.com> <4C1A4A74.9070105@cfl.rr.com> <20100617162747.GA21336@redhat.com> <4C1ACBF1.3050603@cfl.rr.com> <4C1BC125.4090902@sandeen.net> <4C1BC6D0.2030203@sandeen.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4C1BC6D0.2030203@sandeen.net> Sender: linux-fsdevel-owner@vger.kernel.org To: Phillip Susi Cc: Mike Snitzer , device-mapper development , linux-fsdevel@vger.kernel.org, Eric Sandeen List-Id: dm-devel.ids Eric Sandeen wrote: > Eric Sandeen wrote: >> Phillip Susi wrote: >>> On 06/17/2010 12:27 PM, Mike Snitzer wrote: >>>>>> http://git.kernel.org/linus/18e9e5104fcd9a9 >>>>>> http://git.kernel.org/linus/6b0310fbf087ad6 >>>>> Yes, these do look suspicious. I'll test reverting them tonight. >>>> OK, I'd suggest reverting the VFS change (18e9e5104fcd9a9) first. >>> Turns out it was 6b0310fbf087ad6 that did it. CCing Eric Sandeen since >>> he wrote it. Eric, this patch seems to cause a deadlock when taking an >>> lvm snapshot of the root lv. Any idea why? >> I'll look. A sysrq-w when it hangs up would probably be enlightening... >> >> -Eric > > FWIW simple freeze/unfreeze works for me, and lvm snap on a non-root ext4 > partition seems to as well. I'm out for a few days and probably won't > get a root lv set up to test anytime soon. If you can provide sysrq-w > output that probably will be a big help if it doesn't end up being obvious > by inspection. :) Spoke too soon. A little active IO at time of snap did the trick. SysRq : Show Blocked State task PC stack pid father jbd2/dm-2-8 D 0000000000000003 0 1297 2 0x00000080 ffff88013bae8800 0000000000000046 0000000000000000 ffffffff81128046 ffff8800ad876800 ffff8800ad876bb0 00000001007af71d 0000000000000000 0000000000000000 ffff8800ad871024 ffff8800baea1d70 ffff8800ae01ec70 Call Trace: [] ? sync_dirty_buffer+0x7b/0x96 [] ? jbd2_journal_commit_transaction+0x249/0x13e2 [jbd2] [] ? autoremove_wake_function+0x0/0x2e [] ? __switch_to+0xc3/0x1ec [] ? finish_task_switch+0x4c/0x72 [] ? need_resched+0x1a/0x23 [] ? lock_timer_base+0x26/0x4b [] ? try_to_del_timer_sync+0x68/0x74 [] ? kjournald2+0x110/0x33b [jbd2] [] ? autoremove_wake_function+0x0/0x2e [] ? kjournald2+0x0/0x33b [jbd2] [] ? kthread+0x65/0x6d [] ? child_rip+0xa/0x20 [] ? kthread+0x0/0x6d [] ? child_rip+0x0/0x20 dd D 0000000000000001 0 2548 17647 0x00000080 ffff88013ba5c800 0000000000000086 0000000000000000 ffff8800bd889af8 ffff8800be8df000 ffff8800be8df3b0 00000001007af709 0000000000000000 0000000000000000 ffff88010fbf3400 ffff88010fbf3658 ffff88003e9f4c28 Call Trace: [] ? ext4_journal_start_sb+0x84/0x105 [ext4] [] ? autoremove_wake_function+0x0/0x2e [] ? __block_commit_write+0xa4/0xb3 [] ? ext4_dirty_inode+0x13/0x3f [ext4] [] ? __mark_inode_dirty+0x25/0x11e [] ? generic_write_end+0x4d/0x6a [] ? ext4_da_write_end+0x224/0x28c [ext4] [] ? ext4_da_get_block_prep+0x0/0x2ee [ext4] [] ? generic_file_buffered_write+0x164/0x226 [] ? generic_getxattr+0x4c/0x59 [] ? __generic_file_aio_write+0x25d/0x2b1 [] ? should_resched+0x5/0x25 [] ? generic_file_aio_write+0x59/0xa1 [] ? do_sync_write+0xc9/0x10c [] ? autoremove_wake_function+0x0/0x2e [] ? vfs_write+0xa9/0x101 [] ? sys_write+0x45/0x6b [] ? system_call_fastpath+0x16/0x1b lvcreate D 0000000000000002 0 2550 17647 0x00000080 ffff88013ba5e800 0000000000000086 0000000000000000 ffff8800ad8710c8 ffff8800be8df800 ffff8800be8dfbb0 00000001007af718 0000000000000000 0000000000000000 ffff8800ad871024 ffff8800ad871000 ffff8800ad871098 Call Trace: [] ? dev_suspend+0x0/0x1c5 [dm_mod] [] ? jbd2_log_wait_commit+0x112/0x163 [jbd2] [] ? autoremove_wake_function+0x0/0x2e [] ? jbd2_journal_start_commit+0x34/0x6b [jbd2] [] ? ext4_sync_fs+0x74/0x81 [ext4] [] ? sync_quota_sb+0x45/0xe1 [] ? __sync_filesystem+0x3d/0x70 [] ? freeze_bdev+0x8a/0x111 [] ? dm_suspend+0x8a/0x175 [dm_mod] [] ? dev_suspend+0x5b/0x1c5 [dm_mod] [] ? dm_ctl_ioctl+0x22f/0x293 [dm_mod] [] ? place_entity+0x6e/0x95 [] ? __dequeue_entity+0x1b/0x2f [] ? vfs_ioctl+0x21/0x6b [] ? do_vfs_ioctl+0x487/0x4da [] ? pick_next_task+0x1b/0x3c [] ? need_resched+0x1a/0x23 [] ? thread_return+0x9b/0xb2 [] ? sys_ioctl+0x51/0x70 [] ? system_call_fastpath+0x16/0x1b