Re: [uml-devel] Ext4 in user mode linux hang

["Ondřej Kunc" <ondra@czol.eu>]

Hi,

on vanilla kernel (2.6.36 from kernel.org) ... it fails too(so it is not 
debian specific), traces from sysrq t (via uml_mconsole)

(only processess in D state):

jbd2/ubdb-8   D 00000000405068b3     0   580      2 0x00000000
66aea608 660214c8 66021038 60284440 66041cb0 60013597 66aea140 66040000
        66040000 66aea140 66041d10 601d3381 679ac2d0 66bcb8a8 66041d10 
66040000
        00000000 66bcb800 67453a80 1000014a0 66040000 67453b18 66041e50 
60122f6f
Call Trace:
66041c88:  [<60013597>] _switch_to+0x5e/0xae
66041cb8:  [<601d3381>] schedule+0x274/0x2ae
66041d18:  [<60122f6f>] jbd2_journal_commit_transaction+0x16c/0xe59
66041d98:  [<600245e3>] switch_threads+0x2d/0x3d
66041de0:  [<60042f46>] autoremove_wake_function+0x0/0x34
66041e58:  [<6012635c>] kjournald2+0xb8/0x1bb
66041e90:  [<60042f46>] autoremove_wake_function+0x0/0x34
66041eb0:  [<601262a4>] kjournald2+0x0/0x1bb
66041ed0:  [<601262a4>] kjournald2+0x0/0x1bb
66041ee8:  [<60042c9d>] kthread+0x91/0x99
66041f48:  [<60021329>] run_kernel_thread+0x41/0x4a
66041f58:  [<60042c0c>] kthread+0x0/0x99
66041f98:  [<60021310>] run_kernel_thread+0x28/0x4a
66041fc8:  [<6001350f>] new_thread_handler+0x71/0x9b

flush-98:16   D 00000000405068b3     0   609      2 0x00000000
660214c8 608dec08 608de778 60284440 6613b9d0 60013597 66021000 6613a000
        6613a000 66021000 6613ba30 601d3381 6613b9f0 6002a34f 6613ba30 
6613a000
        76800000767 66021000 63474428 00000002 0000ffff 63474440 
6613ba90 601d45a2
Call Trace:
6613b9a8:  [<60013597>] _switch_to+0x5e/0xae
6613b9d8:  [<601d3381>] schedule+0x274/0x2ae
6613b9e8:  [<6002a34f>] wake_up_process+0x10/0x12
6613ba38:  [<601d45a2>] rwsem_down_failed_common+0xb8/0xd8
6613ba98:  [<601d45d5>] rwsem_down_write_failed+0x13/0x15
6613baa8:  [<60027bbb>] call_rwsem_down_write_failed+0x13/0x20
6613bae8:  [<601d3db5>] down_write+0x1c/0x1e
6613baf8:  [<6010053a>] mpage_da_map_blocks+0x308/0x359
6613bb68:  [<60100ce7>] ext4_da_writepages+0x2f7/0x479
6613bc58:  [<6005b236>] do_writepages+0x1c/0x25
6613bc68:  [<60090ab0>] writeback_single_inode+0x93/0x1d4
6613bc98:  [<60090e42>] writeback_sb_inodes+0xa1/0xfe
6613bcf8:  [<60091558>] writeback_inodes_wb+0xc5/0xe4
6613bd00:  [<60042f7a>] wake_bit_function+0x0/0x2e
6613bd48:  [<600916e6>] wb_writeback+0x16f/0x1de
6613bda8:  [<601d3389>] schedule+0x27c/0x2ae
6613bdf8:  [<60091868>] wb_do_writeback+0x113/0x130
6613be08:  [<601d3600>] schedule_timeout+0x13e/0x15c
6613be78:  [<6009190e>] bdi_writeback_thread+0x89/0x13f
6613beb0:  [<60091885>] bdi_writeback_thread+0x0/0x13f
6613bed0:  [<60091885>] bdi_writeback_thread+0x0/0x13f
6613bee8:  [<60042c9d>] kthread+0x91/0x99
6613bf48:  [<60021329>] run_kernel_thread+0x41/0x4a
6613bf58:  [<60042c0c>] kthread+0x0/0x99
6613bf98:  [<60021310>] run_kernel_thread+0x28/0x4a
6613bfc8:  [<6001350f>] new_thread_handler+0x71/0x9b

dd            D 00000000405068b3     0 18357    922 0x00000000
608dec08 60276e98 6087b8c0 6002a1ed 6087b8d0 60013597 608de740 6087a000
        6087a000 608de740 6087b930 601d3381 6087b930 601d7480 6087b930 
6087a000
        816087b920 66bcb800 00000000 67453a80 6087a000 6087b998 6087b9e0 
60122942
Call Trace:
6087b898:  [<6002a1ed>] dequeue_task+0x39/0x48
6087b8a8:  [<60013597>] _switch_to+0x5e/0xae
6087b8d8:  [<601d3381>] schedule+0x274/0x2ae
6087b938:  [<60122942>] start_this_handle+0x2f4/0x395
6087b990:  [<60042f46>] autoremove_wake_function+0x0/0x34
6087b9e8:  [<60122b70>] jbd2__journal_start+0xb9/0xf7
6087ba38:  [<60122bbc>] jbd2_journal_start+0xe/0x10
6087ba48:  [<6010add9>] ext4_journal_start_sb+0xe0/0x125
6087ba78:  [<60015daf>] buffer_op+0xab/0xc7
6087baa8:  [<600ffbf6>] ext4_da_write_begin+0xc1/0x1b4
6087bb28:  [<60054e94>] generic_file_buffered_write+0x124/0x27e
6087bbc8:  [<60088a92>] file_update_time+0x3b/0xfe
6087bc18:  [<60056828>] __generic_file_aio_write+0x380/0x3bf
6087bcd8:  [<600568bf>] generic_file_aio_write+0x58/0xa2
6087bd18:  [<600f80fb>] ext4_file_write+0x92/0xa3
6087bd48:  [<60077c1b>] do_sync_write+0xd1/0x10e
6087bdb8:  [<60015daf>] buffer_op+0xab/0xc7
6087be68:  [<600785ef>] vfs_write+0xb5/0x169
6087bea8:  [<6007875c>] sys_write+0x45/0x6c
6087bee8:  [<60015ab8>] handle_syscall+0x58/0x70
6087bf08:  [<60024ecb>] userspace+0x2dd/0x38a
6087bfc8:  [<60013497>] fork_handler+0x62/0x69

Dne 18.11.2010 19:35, richard -rw- weinberger napsal(a):
> 2010/11/18 Lukas Czerner<lczerner@redhat.com>:
>    
>> On Thu, 18 Nov 2010, Ondřej Kunc wrote:
>>
>>      
>>> Hi,
>>>
>>> I've recently tested ext4 in user mode linux VM. I compiled linux 2.6.36(from
>>> debian source package). I configured kernel this way ... only disabled modules
>>> (to work with default debootstraped debian). Then I created this script:
>>>        
> Can you reproduce this on a vanilla kernel?
>
>    
>>> #!/bin/bash
>>> DD="dd if=/dev/zero bs=1k"
>>> for i in `seq 1 1000`; do
>>>          A=$(($RANDOM%50000))
>>>          $DD count=$A of=frag_$A
>>>          for i in `seq 1 100`; do
>>>                  A=$(($RANDOM%50000))
>>>                  rm -f frag_$A
>>>          done
>>> done
>>>
>>>
>>> This script I'had run on mounted ext4 partition (/dev/ubda ->  /mnt/test). It's
>>> purpose is creating fragmented filesystem to test e4defrag. But after some
>>> time it hungs the whole virtual system. All processes which want to write to
>>> /mnt/test are still in D state. I issued sysrq t via uml_mconsole and in that
>>> output I found traces below.
>>>
>>> Ondra
>>>        
>> I did not look at the traces closely, but did you tried another
>> filesystem ? My experience with UML is that it is always broken so the
>> problem might as well be somewhere else.
>>
>> -Lukas
>>
>>      
>>>
>>>
>>> flush-98:16   D 0000000041a0d8b3     0   811      2 0x00000000
>>> 67c57d80 60276e90 69857980 6002a1ed 69857990 60013597 67c578c0 69856000
>>>         69856000 67c578c0 698579f0 601d3181 69857a10 601d74a0 698579f0 69856000
>>>         ffffffff00000a57 62e09800 00000000 69ab1480 69856000 69857a58 69857aa0
>>> 6012274e
>>> Call Trace:
>>> 69857958:  [<6002a1ed>] dequeue_task+0x39/0x48
>>> 69857968:  [<60013597>] _switch_to+0x5e/0xae
>>> 69857998:  [<601d3181>] schedule+0x274/0x2ae
>>> 698579f8:  [<6012274e>] start_this_handle+0x2f4/0x395
>>> 69857a50:  [<60042f42>] autoremove_wake_function+0x0/0x34
>>> 69857aa8:  [<6012297c>] jbd2__journal_start+0xb9/0xf7
>>> 69857af8:  [<601229c8>] jbd2_journal_start+0xe/0x10
>>> 69857b08:  [<6010abe5>] ext4_journal_start_sb+0xe0/0x125
>>> 69857b28:  [<600fa802>] ext4_meta_trans_blocks+0x5b/0xaf
>>> 69857b68:  [<60100a43>] ext4_da_writepages+0x249/0x479
>>> 69857c58:  [<6005b042>] do_writepages+0x1c/0x25
>>> 69857c68:  [<600908bc>] writeback_single_inode+0x93/0x1d4
>>> 69857c98:  [<60090c4e>] writeback_sb_inodes+0xa1/0xfe
>>> 69857cf8:  [<60091364>] writeback_inodes_wb+0xc5/0xe4
>>> 69857d00:  [<60042f76>] wake_bit_function+0x0/0x2e
>>> 69857d48:  [<600914f2>] wb_writeback+0x16f/0x1de
>>> 69857da8:  [<601d3189>] schedule+0x27c/0x2ae
>>> 69857df8:  [<60091674>] wb_do_writeback+0x113/0x130
>>> 69857e08:  [<601d3400>] schedule_timeout+0x13e/0x15c
>>> 69857e78:  [<6009171a>] bdi_writeback_thread+0x89/0x13f
>>> 69857eb0:  [<60091691>] bdi_writeback_thread+0x0/0x13f
>>> 69857ed0:  [<60091691>] bdi_writeback_thread+0x0/0x13f
>>> 69857ee8:  [<60042c99>] kthread+0x91/0x99
>>> 69857f48:  [<60021329>] run_kernel_thread+0x41/0x4a
>>> 69857f58:  [<60042c08>] kthread+0x0/0x99
>>> 69857f98:  [<60021310>] run_kernel_thread+0x28/0x4a
>>> 69857fc8:  [<6001350f>] new_thread_handler+0x71/0x9b
>>>
>>> jbd2/ubdb-8   D 0000000041a0d8b3     0  4542      2 0x00000000
>>> 6838d640 60276e90 68275ca0 6002a1ed 68275cb0 60013597 6838d180 68274000
>>>         68274000 6838d180 68275d10 601d3181 68fd7470 601d74a0 68275d10 68274000
>>>         00000000 62e09800 69ab1480 1000077f1 68274000 69ab1518 68275e50
>>> 60122d7b
>>> Call Trace:
>>> 68275c78:  [<6002a1ed>] dequeue_task+0x39/0x48
>>> 68275c88:  [<60013597>] _switch_to+0x5e/0xae
>>> 68275cb8:  [<601d3181>] schedule+0x274/0x2ae
>>> 68275d18:  [<60122d7b>] jbd2_journal_commit_transaction+0x16c/0xe59
>>> 68275d98:  [<600245e3>] switch_threads+0x2d/0x3d
>>> 68275de0:  [<60042f42>] autoremove_wake_function+0x0/0x34
>>> 68275df8:  [<600222bb>] set_signals+0x1c/0x2e
>>> 68275e18:  [<60043094>] finish_wait+0x64/0x6f
>>> 68275e58:  [<60126168>] kjournald2+0xb8/0x1bb
>>> 68275e90:  [<60042f42>] autoremove_wake_function+0x0/0x34
>>> 68275eb0:  [<601260b0>] kjournald2+0x0/0x1bb
>>> 68275ed0:  [<601260b0>] kjournald2+0x0/0x1bb
>>> 68275ee8:  [<60042c99>] kthread+0x91/0x99
>>> 68275f48:  [<60021329>] run_kernel_thread+0x41/0x4a
>>> 68275f58:  [<60042c08>] kthread+0x0/0x99
>>> 68275f98:  [<60021310>] run_kernel_thread+0x28/0x4a
>>> 68275fc8:  [<6001350f>] new_thread_handler+0x71/0x9b
>>>
>>> dd            D 0000000041a0d8b3     0  4952   4593 0x00000000
>>> 6838c8c0 67c57d80 67c578f8 60284440 69b6d7a8 60013597 6838c400 69b6c000
>>>         69b6c000 6838c400 69b6d808 601d3181 69b6d7c8 6002a34f 69b6d808 69b6c000
>>>         00001000 6838c400 696c0838 00000001 ffffffffffffffff 00000000 69b6d868
>>> 601d43a2
>>> Call Trace:
>>> 69b6d780:  [<60013597>] _switch_to+0x5e/0xae
>>> 69b6d7b0:  [<601d3181>] schedule+0x274/0x2ae
>>> 69b6d7c0:  [<6002a34f>] wake_up_process+0x10/0x12
>>> 69b6d810:  [<601d43a2>] rwsem_down_failed_common+0xb8/0xd8
>>> 69b6d838:  [<600222bb>] set_signals+0x1c/0x2e
>>> 69b6d870:  [<601d43e9>] rwsem_down_read_failed+0x12/0x14
>>> 69b6d880:  [<60027b98>] call_rwsem_down_read_failed+0x14/0x24
>>> 69b6d8c8:  [<601d3b97>] down_read+0x11/0x13
>>> 69b6d8d8:  [<600fe1cc>] ext4_map_blocks+0x3e/0x18e
>>> 69b6d938:  [<600ffe02>] ext4_da_get_block_prep+0x83/0x2bd
>>> 69b6d958:  [<60095705>] alloc_buffer_head+0x18/0x6c
>>> 69b6d968:  [<60095d31>] alloc_page_buffers+0x75/0xd1
>>> 69b6d9d8:  [<60097105>] block_prepare_write+0x177/0x380
>>> 69b6d9e8:  [<6005588b>] add_to_page_cache_locked+0xbf/0xe7
>>> 69b6da00:  [<600ffd7f>] ext4_da_get_block_prep+0x0/0x2bd
>>> 69b6da98:  [<600973f3>] __block_write_begin+0x12/0x14
>>> 69b6daa8:  [<600ffa62>] ext4_da_write_begin+0x123/0x1b4
>>> 69b6db28:  [<60054ca0>] generic_file_buffered_write+0x124/0x27e
>>> 69b6dbc8:  [<6008889e>] file_update_time+0x3b/0xfe
>>> 69b6dc18:  [<60056634>] __generic_file_aio_write+0x380/0x3bf
>>> 69b6dcd8:  [<600566cb>] generic_file_aio_write+0x58/0xa2
>>> 69b6dd18:  [<600f7f07>] ext4_file_write+0x92/0xa3
>>> 69b6dd48:  [<60077a27>] do_sync_write+0xd1/0x10e
>>> 69b6ddb8:  [<60015daf>] buffer_op+0xab/0xc7
>>> 69b6de68:  [<600783fb>] vfs_write+0xb5/0x169
>>> 69b6dea8:  [<60078568>] sys_write+0x45/0x6c
>>> 69b6dee8:  [<60015ab8>] handle_syscall+0x58/0x70
>>> 69b6df08:  [<60024ecb>] userspace+0x2dd/0x38a
>>> 69b6dfc8:  [<60013497>] fork_handler+0x62/0x69
>>>
>>> bash          D 0000000041a0d8b3     0  5324   5271 0x00000002
>>> 67e2c540 60276e90 67dcfbd0 6002a1ed 67dcfbe0 60013597 67e2c080 67dce000
>>>         67dce000 67e2c080 67dcfc40 601d3181 62a31000 601d74a0 67dcfc40 67dce000
>>>         67dcfc10 62e09800 00000000 69ab1480 67dce000 67dcfca8 67dcfcf0 6012274e
>>> Call Trace:
>>> 67dcfba8:  [<6002a1ed>] dequeue_task+0x39/0x48
>>> 67dcfbb8:  [<60013597>] _switch_to+0x5e/0xae
>>> 67dcfbe8:  [<601d3181>] schedule+0x274/0x2ae
>>> 67dcfc48:  [<6012274e>] start_this_handle+0x2f4/0x395
>>> 67dcfca0:  [<60042f42>] autoremove_wake_function+0x0/0x34
>>> 67dcfcf8:  [<6012297c>] jbd2__journal_start+0xb9/0xf7
>>> 67dcfd48:  [<601229c8>] jbd2_journal_start+0xe/0x10
>>> 67dcfd58:  [<6010abe5>] ext4_journal_start_sb+0xe0/0x125
>>> 67dcfd60:  [<6008424f>] filldir+0x0/0x11a
>>> 67dcfdb8:  [<600fb08a>] ext4_dirty_inode+0x1b/0x48
>>> 67dcfdd8:  [<60091027>] __mark_inode_dirty+0x29/0x199
>>> 67dcfdf8:  [<60088a63>] touch_atime+0x102/0x125
>>> 67dcfe38:  [<6008424f>] filldir+0x0/0x11a
>>> 67dcfe48:  [<600844fd>] vfs_readdir+0x7a/0xa1
>>> 67dcfe98:  [<6008469d>] sys_getdents+0x90/0x124
>>> 67dcfee8:  [<60015ab8>] handle_syscall+0x58/0x70
>>> 67dcff08:  [<60024ecb>] userspace+0x2dd/0x38a
>>> 67dcffc8:  [<60013497>] fork_handler+0x62/0x69
>>>
>>>
>>>        
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>>
>>      
>
>
>    


-- 
Ondřej Kunc

správce serverové farmy
CZOL media interactive s.r.o.
Sídlo: Moulíkova 2238/1, Praha 5, 15000
Kanceláře: Na Moráni 5357, Chomutov, 43001
Telefon: +420 723 137 981
E-mail: ondra@czol.eu
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